Here's why:
* It modifies verbs, adjectives, or other adverbs: It tells us *where* something isn't happening or where something is not located.
* Example: "I looked nowhere for my keys." (modifies the verb "looked")
* It can be used as a pronoun: In some cases, it can stand in for a place.
* Example: "I've been nowhere lately." (stands in for a place)
Let me know if you'd like more examples!