In physics, angular speed is the angle through which an object has moved about the axis of rotation divided by the time it takes to go through that angle.

In equation,  we get : 

Angular speed = (Rotation angle) / Time 

Usually we use radian as the unit for angular speed. For example, if an object travels through an arc of length s meters along a circle which has a radius of r meters, than the angle will be s/r radians.