Rotate means to circle around a center point. Wheels on a car rotate, planets rotate, and if you're an ice skater, you rotate on the blade of a skate when you do your spins.
Rotate can also mean that you take turns performing a job. If you, Jim, and Shelia all got the same amount of votes in the class election, you could rotate the role of treasurer, meaning the position would pass from one to another in a regular pattern. Rotate can also refer to other things that are passed along in a regular order. You might rotate lawn duties with your brother — that means you mow the lawn one week and he mows it the next.