An issued developer token is a unique combination of letters, numbers, and characters that is required for communicating with the Google Ads API server. It authorizes your Google Ads API activity and thus you should treat it like a password.
What happens on reset?
A reset will immediately invalidate your previous token, so any API requests using the old token will fail. However, a reset will not trigger a re-review and approval for the new developer token. You can start using the new developer token immediately.
How do I reset my developer token?
Sign in to your Google Ads Manager Account.
Click TOOLS & SETTINGS (wrench icon) on the top right corner of the screen.
Under SETUP, select API Center.
Under API Access, expand the Developer token section.
Click Reset token.