The Profile Rotate tool will take a line (any set of inputs: curve, points, etc from a probe) and change the starting point. This will then rotate all the information that was a part of the starting point to the back.
Example: if we started with a curve or a set of points within a curve (original line) and we decided that the starting point would be better off in a different spot (at the red line) the starting point will then be moved and recreate the furve useing the new starting point. The old starting point will just be shifted in order to the end.