How do I know if I have a Google Pay compatible phone?

Check Android version:

Open your phone's Settings app
Near the bottom, tap System And then System update
See your "Android version" and "Android security update".

Check NFC:

Open “Settings
In the ‘Search settings’ bar, type ‘NFC’
Tap and turn on NFC.

If you can’t find NFC, your Android phone can’t make contactless in-store payments; however, you will still be able to use your phone to make payments on websites and in apps.

For more details, go to Fix problems with tap-to-pay transactions - Google Wallet Help.