GMB stands for Google My Business
Google My Business, or GMB, is a Google property that allows for businesses to claim their existence on Google Properties based on their physical location. Claiming your business through Google My Business provides your business with access to Google Map’s search results and also in Google’s Local Graph on the right-hand side of Google’s SERP.
Google My Business Features
There are many features that are provided through Google My Business, including listing your phone number, business information and hours, as well as creating posts, uploading images/videos and placing virtual walkthroughs of your business.