Uniform circular motion is when something is moving in a circle at a constant speed. Imagine you are spinning around and around on a merry-go-round. You are moving in a circle and going the same speed the whole time.
When you are in uniform circular motion, there are two main things you need to know: the speed you are going and the radius of the circle. The radius is the distance from the center of the circle to the edge. If you are spinning faster, you will go around the circle more times per second. If the radius is bigger, you have to go faster to get around the circle in the same amount of time.
Another important thing to know is that there is a force keeping you in the circle. This force is called the centripetal force, and it is what makes you turn instead of going straight. If you were in a car and turned the steering wheel to the left, the force of the wheels on the road makes you turn left. In uniform circular motion, the centripetal force is what makes you turn.
Overall, uniform circular motion is when something moves in a circle at a constant speed. The speed and radius are important, and the centripetal force keeps you turning in the circle.