If you look at the string, it's a straight line from the bridge to the nut (if it's tuned up, that is

), but at the nut, it changes angle as it goes to the tuner. That is the breaking angle.
How to adjust it?
Either get a new string, leave it longer then the previous one, and wind it lower, nearer to the bottom of the tuner to have a bigger angle. Or rewind the string like this.