first off welcome to AF!!!!!!!!!!!!!
second, you will need a better picture. can't even make out what the icon is.
and thirdly,
we get this question almost on a daily basis where most of them go unanswered. the problem is that there are millions upon millions of apps out there, each with their own notification icon.......so unless it is something like facebook or youtube, the chances of recognizing an app just from it's icon is very small. the only true way of knowing is to look into the phone's notifications or look into the app drawer as the icons are usually of the same used for the app icon. however, most of the cases the phone cannot be access for various reasons. the easiest way (well maybe harder than it sounds) is to just ask the person who owns the phone.
anyways, if you can get a better screenshot or picture of the icon, you might get lucky with someone recognizing it.