Notifications for setting app

That notification badge indicates one of two things:

• You have an iOS update ready to install
• or, I think, if this is a new phone, you have configuration items to complete (and if you chose not to complete those, it will go away shortly.

I either case, have you opened the Settings app to see what it might be trying to tell you?

And if you open Settings, what do you see in there, anything?

Then I would suggest powering the iPhone off and back on again and it should clear. The device should realize that it has the latest iOS at that point.