While each scammer is unique, they all typically open with "I'm calling on behalf of Google" and then telling you that something is wrong with your Google listing. Usually something along the lines of:
The point of this phone call is for you to accept the help of the scammer in exchange for a fee. It might be $100, or $1,000.
You may receive calls from Google operators for the purposes of customer service or support related to your Google Ads or other accounts but they will never make unsolicited sales calls and ask for your payment information over the phone.
The major phone carriers have tools to identify and filter suspected spam calls. While caller ID services usually require an extra monthly fee, some carriers offer network-level blocking free of charge.
AT&T users can download the free app AT&T Call Protect to automatically block suspected spam calls suspected spam warnings.
Verizon has ways to help you block calls on your home phone on your home phone. If you are a Verizon Fios Digital Voice customer you can register with Nomorobo. For mobile users, Call Filter screens incoming calls, auto-blocks spam and reports any unwanted numbers.
T-Mobile users will see "Caller Verified" when an incoming call has been verified as authentic by the network. This means that the phone number has not been spoofed.
T-Mobile also offers Scam ID, which identifies spam numbers when your phone rings, and Scam Block, which gives you an option to block those numbers. To turn this on, dial #662# on your T-Mobile phone. To turn it off, dial #632#.
Sprint users can sign up for the Premium Caller ID service for $2.99/month to receive threat level indicators on incoming calls, but the service doesn't automatically block spam calls.
There are also mobile apps like RoboKiller that do the job.
Read more about known Google scams.