Have you ever gone to a place like a park, where you can play around and see trees and animals? A nature reserve is like a really big and special park, where people aren't allowed to build houses or change the land in any big ways. It's there to help protect the plants and animals that live there, and make sure they don't disappear.
It's like when you have a toy that's super special to you, and you don't want anyone to mess it up or take it away. The people who take care of the nature reserve feel that way about the plants and animals there, and they work hard so they can keep living and growing.
They even have special rules, like not letting people pick the flowers or feed the animals, so they won't get hurt. It's important for us to have nature reserves because they help keep our planet healthy and beautiful, and we can still have fun visiting them and enjoying all the amazing things they have to offer!