Google App provide us a way in order to socialize (or advertise) your application from user-to-user. There are multiple cases in order to implement Google App invite.
Case 1: If we want to send the invitation to user's close friend we can just share the Play store URL of the app with some other information. (if we want that share with those users that have interests in Salaat tracking)
Case 2: If we want to share something with other users via email and SMS. Like to share any discount offer in the application, or users wants to share their prayer rate (in Salaat Tracker). For this, we have to enable deep linking.
App invites offers a list of friends list (most probably google contact list) whom user want to share the app.