Okay, so imagine you have a friend named Nim. Nim is not a human like you, but he's also not an animal like a dog or a cat. He's something in between - he's a chimpanzee! Chimpanzees are very smart animals and they can do a lot of things that humans can do too, like using tools and communicating with each other.
Nim was a special chimpanzee because humans were trying to teach him how to communicate with them using sign language. Sign language is a way of using your hands and body to make different shapes and movements that mean different words or ideas. Nim was very good at learning sign language and he could communicate with the humans who were teaching him.
The humans who were teaching Nim wanted to see if he could use sign language to tell them about his thoughts and feelings. They wanted to see if he was really communicating with them or if he was just copying what they did. So, they would ask Nim questions and see if he could answer them using sign language. They would also observe his behaviors to see if they could figure out what he was feeling.
Nim became famous because he was one of the first chimpanzees to learn sign language and communicate with humans. He helped scientists learn more about how animals communicate and think. However, it was also controversial because some people thought it wasn't right to keep a wild animal like a chimpanzee in captivity and teach him to live like a human.
So, that's Nim Chimpsky - a special and smart chimpanzee who was able to communicate with humans using sign language.