Okay kiddo, let me explain what a capsule of lens is in a simple way. Imagine you're wearing glasses that have a lens in them. Now, the lens in your eye is very similar to the one in your glasses, but it's a natural lens that your body has made all by itself.
Now imagine that there is a thin, clear layer around that natural lens inside your eye, like a protective blanket. That is called the capsule of lens. It's like a clear plastic sleeve that keeps the lens safe and in place.
As you grow older, your natural lens may become cloudy or even change shape. When this happens, doctors can remove the cloudy lens and replace it with a new artificial one. But, they often leave the capsule of lens in place and put the new lens inside it, kind of like putting a new lens in a new case.
That way, the new lens stays in the right spot and is protected just like the old one was. Pretty cool, huh?