Relatives Around Me is a new addition to the Family Tree App for iOS and Android devices.
You can find the Family Tree App in the FamilySearch.org App Gallery.
Relatives Around Me allows you to see if you are related to people who are physically nearby and using the same app. We tried it and found out that I am an 11th cousin twice removed to my wife. Of course, as with all these Family Tree dependent apps, any relationship shown depends on the accuracy of the data in the Family Tree. But this app should be able to settle any discussions about relationships among those who are reasonably closely related such as at a family reunion.
It is not a separate app, it is part of the Family Tree app.