Basically not much. You can use them to:
A. Rent certain clubs in the Pro Shop (a step or 2 above the basic clubs you're given to start with)
B. Upgrade apparel higher levels
C. Play coin games to win more coins
I don't want to come off as an A-hole since you are kind of new and it's likely you don't know, but there is a search box over to the right -->. You can find a wealth of info about this game using this.