Imagine a big ball, like a snow globe, but instead of snow inside, there are thousands of tiny lenses stuck to the surface. These lenses are like the lenses in your glasses, but much smaller! Now imagine that this ball is actually a dome, like the top of a castle.
This dome, called a "fly's eye dome," is used to see things from all directions at once. When you look through one of the lenses, you can see a small portion of what's around the dome. But when you look at all the lenses together and combine all of the small views, you get a big picture of everything around the dome.
This can be really useful for things like monitoring the weather or tracking airplanes in the sky. Instead of just looking in one direction, the fly's eye dome can see everything in a 360-degree view at the same time!