When you do the Security Checkup, the first step is to make sure that you have your correct cell phone number and recovery email address just incase you forgot your password, or for unusual activity on your account. After you confirm (or update) that information, it will show you some recent security related events (like if you changed your password, added an email address, etc).
Then, after all that looks good (unless something didn’t look good, then click “Something looks wrong”), you’ll be shown all of your connected devices. Unfortunately, it doesn’t show the IP address for the device, and in the past, we have seen were it will give the wrong city (that was very common with cellphones. For us, our cell phones showed up coming from Chicago, IL, though it appears Google has altered that to say United States to side step that and reduce panic). As you can see… SchaOn logs in on many, many machines:
Next, the Security Checkup will show you all applications, websites, etc that have permission to integrate or access all or parts of your Google Account information. After that, if you’ve setup any specific App Passwords — for example if you have 2-step Verification turned on (a really nice, free, security enhancement for your account) — for applications like Outlook or the old Google Talk. Next it will take you through checking settings within your Gmail account like if you have forwarding addresses setup, or if you’ve authorized people to see your email from their Google Account and act on your behalf. Lastly, they will have you check your 2-step verification settings to make sure those are up to date.
Overall, it’s pretty simple, takes only a few minutes.