When you think a person's hair cut, makeup, or clothes match that person well, and make that person look good, you can say that it "looks good on" them:
Oh wow, that dress looks so good on you!
This might seem natural for talking about clothes because you put them on, but you can also talk about hair this way:
I think that's a nice hair style on you.
Or just this:
That's a nice look on you.