Peter V. answered 07/08/13
I teach all math from HS Algebra I to Calc III, prob & stats
Robert is correct but just for a little more detail:
one full rotation of any circle (meaning the unit circle included) has an angle measure of 2pi radians, when they say -.6 rotations they mean .6 of a rotation in the negative angular direction, thus as Robert writes
(-.6)(2pi)= -3.77