Where is the icon? On a homescreen or a notification? I'm going to assume notification, because that's what these questions are usually about, but as the icons are not identical and you've cropped all of the context away it might help someone to know.
In any case I have to warn you that most of the time we cannot answer these questions: there are literally millions of apps out there, so unless it's a fairly well-known one the odds are not in your favour. Although you presumably don't want to do this (because otherwise why ask a bunch of strangers on the internet?), in most cases the only way you'll find out is if you ask the person whose phone this came from.