I’m guessing they mean using it as an anti-theft device. If a thief steals an item with a tracker in it, they’ll be notified of the tracker’s presence by their phone and remove it. Of course, these trackers aren’t anti-theft devices and you probably shouldn’t use them to try confronting a thief on your own anyway…
The self healing part is for scratches on the inner screen. Since the inner screen can’t be made of glass, it’s prone to scratches.