Hey kiddo! Have you heard of the word "biogeographic realm"? It's okay if you haven't, I'll explain it to you.
So imagine our planet, Earth, as a giant puzzle piece. Each piece of the puzzle is like a different area or region, kind of like how different rooms in our house have their own things in them. In the same way, Earth has different regions that contain different plants and animals.
Now, the biogeographic realm is just a fancy way of saying a big puzzle piece where similar kinds of plants and animals live. For example, you might have heard of the rainforest - that's a biogeographic realm because it has a lot of different plants and animals that live there that are different from say, the desert or the Arctic.
Scientists use biogeographic realms to study how plants and animals evolve and adapt to their different environments. It's kind of like a big map that helps them understand where different species come from and why they are unique to certain areas.
So now you know that a biogeographic realm is just a big area of the Earth where similar plants and animals live, like a puzzle piece that's part of a bigger picture!