Okay kiddo, so have you ever played with a flashlight? It makes things bright and visible in the dark, right? Well, that's what we call a "flash."
Now imagine you have a big circle made out of paper or something. If you fold it in half like a taco, you have two halves of the circle, right? And if you keep folding it in half again and again, you get smaller and smaller pieces, until you can't fold it anymore. This is what we call a "circle."
So, what do flashes and circles have to do with each other? Well, sometimes people use flashes to light up circles. They might do this to create a special effect, or to show something off. For example, if you were playing with a hula hoop at night, someone could shine a flashlight on it to make it look really cool.
Does that make sense, kiddo?