This might be because the time on your Google Authenticator app is not synced correctly.
To make sure that you have the correct time:
- Go to the main menu on the Google Authenticator app
- Tap More Settings.
- Tap Time correction for codes
- Tap Sync now
On the next screen, the app will confirm that the time has been synced, and you should now be able to use your verification codes to sign in. The sync will only affect the internal time of your Google Authenticator app, and will not change your device’s Date & Time settings.
On iOS (Apple iPhone):
- Go to the iPhone Settings App. (your phone settings area)
- Select General
- Select Date & Time
- Enable Set Automatically
- If its already enabled, disable it, wait a few seconds and re enable