If a moving body has a circular movement, it is easier to express its speed by counting the number of revolutions it makes per unit of time than the metres it covers per unit of time. This is why in circular movements we use terms like: revolutions per minute, radians per second or revolutions per second.

Knowing how  many times it revolves per second or per minute gives us an idea of how quickly it is moving.
We use the word "revolution" to express when an object completes a circuit so that the speed of a UCM is usually expressed in: r.p.m. ( revolutions per minute)

We also use the term r.p.s. (revolutions per second). Angular velocity is the term for the radians it covers in a second.

Another simple way to say how quickly a UCM is moving is to express how long it takes to complete a revolution; this magnitude is also called period.

You can revise all these terms in Uniform circular movement 4th year