If you're talking about when it says Name (Insert number), it means that's how many times they've called you or you've called them, in a row. For example, when I call someone, call them again, then call later without receiving or making any other calls, it would place a 3 there since I called them 3 times.
Before anyone else, you can tap and see what they are. For example if you only got called by 1 person in 5 days. It will show only them with as many times as they called in those days
