OK kiddo, so when you look at pictures, you can tell if they are blurry or not, right? The blurriness is how clear the picture is. When we say "high resolution," we mean REALLY clear pictures - like when you can see every little detail very clearly.
To make a high resolution picture, we need a special camera or tool that can take a lot of tiny little pictures all at once. Each tiny little picture is called a pixel. So a high resolution picture has a LOT of pixels that make it really clear and detailed.
Sometimes we need high resolution pictures for important things, like seeing details in a medical scan or looking at a crime scene photo to try and solve a mystery. But it can also be fun to have high resolution pictures of pretty things, like sunsets or cute animals.
So, in summary, a high resolution picture is a really clear and detailed picture that is made up of lots and lots of tiny little pictures called pixels.