The Companion App is a feature in Tom Clancy's The Division
It is part of the Companion Gaming mechanic
The Companion App lets you support your teammates using a tablet such as an iPad. You will be controlling a Companion Drone and supporting your allies by Healing them, Buffing them, Debuffing the enemies, Firing Missles, and more
EDIT : 06/23/2015 The Companion app has been canned. See http://www.eurogamer.net/articles/2015-06-23-the-divisions-companion-app-has-been-canned
