Users have the option to "follow" places that they'd like to receive updates from. When a user follows a place they see that place's offers in the at the very top of their screen when they open the app. We also use this information along with other data signal when determining which events within the app users should receive push notifications about. For more information about the following feature see the user support article about following places.
This number is the total of all users who have chosen to follow your place.