CITES is like the superhero of the animals and plants. It is a group of grown-up people who make rules to protect animals and plants in danger. They created a list of animals and plants that need special protection because people like to hunt them or collect them from nature.
This list is like a big secret book that only CITES knows and everybody who wants to sell or buy animals or plants on this list must follow the rules of the book. If they don't follow the rules, then they can get into trouble with the police.
For example, if someone wants to buy or sell a really cool parrot that's in the secret book, they must prove that they got the parrot in a legal way and not by catching it in the wild. Then, they can get a special paper from CITES that shows they followed the rules.
CITES makes sure that the animals and plants get extra protection so they can keep living and growing in their natural habitats, and we can keep enjoying their beauty for many years to come.