Nouns head nominals, which head noun phrases (NPs). The most common NP functions are subject, object, and predicative complement. Nouns mostly inflect for number: singular or plural. Pronouns are a special subset of nouns which also inflect for case. A nominal includes a head noun and any internal dependents. Unlike most phrases, nominals can have adjective-phrase modifiers, and NPs uniquely may have a constituent in determiner function.
Though it’s true that only nouns denote ‘people, places, and things’, they denote almost anything, including actions. Along with number, the semantic notion of definiteness and the count/non-count distinction affect the choice of determiner. Subject-verb agreement is also affected, for example, with measure expressions. Determiners are usually determinative phrases or genitive NPs. Nominals allow complements, usually preposition phrases. NPs also have a range of external dependents, including predeterminer modifiers. Determiners and modifiers may function as fused heads, in which case, the NP may not actually include a noun. The pronouns, including personal, relative, and interrogative types, have deictic and anaphoric uses and notably have gender.