Kanzi is a bonobo (similar to a chimpanzee) who can understand language (abstract geometric symbols and speech). Earlier attempts to teach language to apes met with limited success, but Kanzi is amazing, and is rewriting the book on the subject!

Here is a series of three videos showing what the amazing Kanzi can do. He can understand a few hundred words, follow a conversation, start a fire, play a video game, etc ...