The goal of the Rotator is to do bulk rotation of text objects on your design. You chose the old rotation value you want to change and the new rotation value you want it changed to as well as the class/subclass layers where the text is written, and the Rotator does all the work for you.
Since in many situations you'd want to change more than one rotation value, you are given three "Rotation Groups" to work with so you can simultaneously change more than one rotation.
You can either use the default set of classes and subclasses where text normally hides or you can manually pick your own class and subclasses. You can pick multiple subclasses from the provided list by holding down the Shift/Control keys while clicking on them.
Once you choose the rotations you want to change and make sure you're going to operate on the class/subclasses you want, just hit the "Rotate" button and all the rotation changes are made for you.