I'm assuming by points you meant points as in the ones under posts, and not rep, correct?
Points are accumulated by posting on the forums. In turn, you can use these points in the "store" area of the site. Provided you have enough points, you can do things like buy colored user names, change your title that appears under your username, change your username, you can buy a glowing username, etc. Also you can "invest" points in the bank and gain interest. I think you get an extra 10% daily. Basically points are these forums form of currency.