Here's why:
* The definition of a verb: A verb is a word that describes an action, state, or occurrence.
* The sentence "The verb is a verb": This sentence uses the word "verb" to describe itself. It's like saying, "This statement is false."
* The paradox: If "verb" is a verb, then the sentence is true. But if the sentence is true, then "verb" must be a noun (describing the word itself), making the sentence false.
It's a fun linguistic puzzle, but it doesn't have a straightforward answer!