Meaning: This sentence is describing how the chameleon's skin changes to match the color of the wall. This is a special ability that chameleons have.
Choice of Words: The word "chameleon" is a noun that refers to a type of lizard that can change the color of its skin. "Skin" is the outer layer of an animal's body. "Changed" is a verb that means to become different. "Match" means to be similar or identical to something else. "Wall" is a structure that separates or encloses an area.