Pronouns in French are words used to replace nouns in a sentence, helping to avoid repetition and make communication smoother. They include subject pronouns like "je" (I), "tu" (you), "il/elle" (he/she), object pronouns such as "le" (him/it), "la" (her/it), reflexive pronouns like "se," and possessive pronouns indicating ownership. Understanding how to use pronouns correctly is essential for forming clear and natural sentences in French.