What this tile shows
Squizzie calls this one Google Rating. It reads as a star rating out of five.
Where the number comes from
Google Business Profile. Local search visibility, customer actions, search keywords, and reviews from Google Business Profile.
What you need for it to appear
A connected Google Business Profile location, through the same single Google sign-in.
The fuller picture
This is one figure out of a bigger subject. Search rankings and your local listing covers it properly.