Pronouns are words like “I,” “she,” and “they” that are used in a similar way to nouns. They stand in for a noun that has already been mentioned or refer to yourself and other people.
Pronouns can function just like nouns as the head of a noun phrase and as the subject or object of a verb. However, pronouns change their forms (e.g., from “I” to “me”) depending on the grammatical context they’re used in, whereas nouns usually don’t.