With a USB cable, you can connect your Android device to your computer to explore the files it contains just like any other USB device. If you are using a Mac, this will only be possible with a special program created by Android developers called Android File Transfer. You can also use a cross-platform program called AirDroid which enables fast wireless transfers.
Steps
Method 1 of 3: Use macOS

Step 1. Open the Android File Transfer site on your Mac
To connect your Android device to your Mac and explore the files it contains, you will need a special program called Android File Transfer.
In Safari, type android.com/filetransfer/ to open the download page

Step 2. Click Download Now
The installation file will be downloaded to your Mac.

Step 3. Open the installation file
The download should only take a few seconds (even for slow connections), as the DMG file is only a few megabytes long.

Step 4. Drag Android File Transfer to the Utilities folder
The 2 icons will appear in the window that will open when you run the installation file.

Step 5. Open the Applications folder
Click on the menu Go on the desktop and select Applications.

Step 6. Launch Android File Transfer
To start Android File Transfer, click To open at the command prompt. The command prompt only appears after the first installation.

Step 7. Unlock your Android screen
To allow your Mac to access your Android's memory, you need to unlock its screen.

Step 8. Connect your Android to your Mac by USB
If your Android's settings are already correct, the Android File Transfer window should come to the fore.

Step 9. Open the notification panel on your Android
To open the panel that displays all of your notifications, swipe down from the top of the screen.

Step 10. Tap the USB option
Choose the mode you want to use for your device. In your notification list, look for the USB logo.

Step 11. Select Transfer Files, Transfer Media, or MTP
This mode allows you to connect your Android to your Mac as if it were a USB device. Your phone's content will be displayed in Android File Transfer.

Step 12. Explore your files in the Android File Transfer window
Similar to Finder, Android File Transfer will display the folders on your device.

Step 13. Disconnect your Android when you are finished
When you have finished transferring or viewing files on your Android, you can disconnect it from your Mac by removing the cable. Make sure there is no transfer in progress before disconnecting it.
Method 2 of 3: Use Windows

Step 1. Connect your Android to your computer
Using a USB cable (you can use the one you use to charge your device), connect your Android to your computer.

Step 2. Pull down the notification panel
Swipe down from the top of your Android screen to view all of your notifications.

Step 3. Choose the USB option
The USB option is in the notifications panel that you just opened and displays the USB logo.

Step 4. Select Transfer Files, Transfer Media, or MTP
The name of the USB option varies from device to device, but once you select it, you will see your Android appear on your computer as a USB device.

Step 5. Wait for the drivers to install
Windows will automatically download the drivers that will allow your Android to communicate with your computer. If the driver installation fails or Windows cannot find them, you will need to install the drivers provided by the manufacturer.
On Google, type "drivers for (phone model)" then follow the link that redirects to the manufacturer's site. Do not download any drivers from unknown sources

Step 6. Open the My Computer / This PC window
In this window you will find all devices and hard drives connected to your computer. If you want, you can open it from the menu To start up or press ⊞ Win + E.

Step 7. Double click on the Android device
In the window, your device will be identified by its model number and will appear under the section Peripherals and drives Where Devices using removable storage devices.

Step 8. Explore the files on your Android
Once your device is open in the window This computer / This PC, you will see the different folders that your device contains. These include the DCIM (camera), Photos, Videos, Music and Ringtones folders. Applications are usually found in separate folders for each application.

Step 9. Eject your device
When you are done moving or accessing files on your Android, click the button Safely remove material in the notification area of your desktop (bottom right of the screen). Select Eject device to eject your device.
You may need to show hidden icons in the notification area to find the Safely Remove Hardware button
Method 3 of 3: Use AirDroid for a wireless connection (on Mac and Windows)

Step 1. Install the AirDroid app on your Android
The AirDroid app is available for free download from the Google Play Store. It will allow you to connect to AirDroid on your computer and transfer files wirelessly.

Step 2. Create an AirDroid account
AirDroid makes it easier to connect your Android and your computer. If this is your first time starting the app, tap To log in and follow the on-screen instructions to create an account.

Step 3. Download AirDroid for your computer
The desktop app is available as a free download for Mac and Windows at airdroid.com. Scroll down the page and click the download button to install the correct version for your operating system.

Step 4. Run the AirDroid installer file
Once the installation file has downloaded, double click on it to install the application on your computer.
If you do not want to install other additional programs, decline the McAfee Web Advisor installation offer

Step 5. Allow access through Windows Firewall
Once the app is installed, launch it and change the Windows Firewall restrictions to allow access to AirDroid. This will allow wireless access to your Android device.

Step 6. Log in to the AirDroid PC application
Use the same account as the one used on the mobile app. You will be automatically logged into your phone.

Step 7. Transfer files from your computer to your Android
Drag and drop the files you want to transfer to your phone into the AirDroid window. Click on Transfer files, go to the tab Device then drag the files you want to add to your Android.

Step 8. Send files from your Android to your computer
From the main menu of the AirDroid app, tap Transfer files, choose AirDroid Desktop then select the files you want to transfer. The files in question will be transferred wirelessly to your computer.