What does an electrostatic motor do?

I am trying to make a robot, but I don't know what kind of motor I should use. So could you tell me what an electrostatic motor does, and how it does it?

An electrostatic motor might be good for making some nano-robots, and an ion thruster might be good for satellites. But for practical normal-sized robots, you need some other type of motor.

I would suggest that you research ready-made servo motors.