Here's why:
* It names a person or thing: It refers to the top part of a body, or the leader of a group.
* It can be the subject of a sentence: "The head is important for thinking."
* It can be the object of a verb: "I scratched my head."
* It can be used with articles and adjectives: "The big head", "a bald head"
Let me know if you have any other words you'd like to check!