To share files via Google files app first of all you need that app installed on your phone if not you can install it by this link : - https://play.google.com/store/apps/details?id=com.google.android.apps.nbu.files
Now Open the app and select the files to transfer.
After selecting files tap on share icon available above side of the app.
You will see a many more sharing options, select the files by Google app.
The. It will ask you to turn on location service you have to turn it on.
Then it will ask you to turn on wifi you have to turn on wifi.
Then it will scan for the receiver.
Ask your friend to open the app and tap receive.
After connection is built. Then files will be transferred.
After everything complete make sure you turn off location and wifi manually.You can comment below if you have any queries..