A (usually closed) class of words that can replace nouns.
Pronouns are one of the parts-of-speech. In modern grammars, pronouns are strictly nominal. They comprise personal pronouns (I, you, etc.), relative pronouns (that, who) and interrogative pronouns (who, what) and some other types. Traditional grammar also called some determiners and some adverbs pronouns (e.g., demonstrative or possessive pronouns/determiners).
The class of pronouns is usually a closed class with few members, but it can be open, specially in East-Asian languages with complicated systems of honorifics.
