“Hole in one!” is a expression used when a golfer gets their golf ball in the hole in only one stroke. However, it can also be used in other circumstances. It can mean that you succeeded on your first try. Read this dialog to see how else you can use it:
Paul – I scored a hole in one today!
Pete – Really? You golf?
Paul – No, not me, but I sold my house right after the first viewing!
Pete – Wow, that is a hole in one, especially in this economy.