Okay kiddo, so imagine a circle, you know what a circle is right? And now imagine that circle is cut in half, so you have only half of it left. That half of the circle is called a half ring.
It's like when you cut an apple in half, you have two halves of the apple, right? Or when you cut a pizza into slices and you take one slice, that's like taking a half ring out of the pizza.
So a half ring is just like half of a circle or half of a ring. It's like having a ring that's been cut in half, so you only have the top half or the bottom half.
Does that make sense to you, kiddo?