That email from Google isn’t spam. Google is now requiring businesses to complete Advertiser Verification in an effort to have more transparency with their advertising on their platform; “To provide a safe and trustworthy ad ecosystem for users, and to comply with emerging regulations.”

If you do not complete advertiser verification, or start the process by the time indicated by Google, your ads will be paused until further notice. You have 30 days to complete the verification process. 

You can read more about advertiser verification here: https://support.google.com/adspolicy/answer/9703665?hl=en