The word "she" is not a noun; it is a personal pronoun. It is used to take the place of a noun in a sentence, typically referring to a singular female person or animal. Thus, "she" functions as a pronoun, not as a noun.
While "she" represents a female entity, it is grammatically classified under pronouns, specifically as a third-person, singular, feminine pronoun in Modern English. Some dictionaries informally list "she" as a noun in contexts where it refers to a female (such as a female animal), but this is a more colloquial or informal usage; the primary and correct classification is that "she" is a pronoun.
