The rotation sensor can be programmed to wait for a certain number of sensor counts. Recall that there are 16 counts per one revolution of the rotation sensor.

This program turns on motor A and waits until the rotation sensor reads 80 counts, then turns off motor A. This would be 5 complete revolutions of the motor axle. Don't forget to reset the rotation sensor!

There is also a rotation sensor fork. In this program, if the number of rotation sensor counts is 80 or less, it lets motor A run. Once the number of counts is above 80, it stops motor A.
Remember that all forks need a fork merge icon at the end of the decision.