An angle is a measure of how much something turns or moves around a point. A degree is a way to measure that angle.
Imagine you are standing at one end of a line and you want to look at something on the other end of the line. If you turn your head to the side, you are making an angle. If you turn your head a little bit, that angle might be 10 degrees. If you turn your head a lot, that angle might be 90 degrees or even 180 degrees.
So a degree is just a number that tells you how big or small an angle is. Think of it like a scale or a ruler for measuring angles. And it's called a "degree" because it's based on dividing a full circle (like the circle you make when you turn your head all the way around) into 360 equal parts, or degrees.