El libro es mío.
English: The book is mine.
Possessive pronouns in Spanish are words used to show that something belongs to someone. They replace a noun and indicate ownership.
Use possessive pronouns in Spanish to say that something belongs to a person or group, and to avoid repeating the noun. They must agree in gender (masculine/feminine) and number (singular/plural) with the object owned.
El libro es mío.
English: The book is mine.
¿Es esta casa tuya?
English: Is this house yours?
Los zapatos son suyos.
English: The shoes are theirs/his/hers/yours (formal).
Estas mochilas son nuestras.
English: These backpacks are ours.
¿Dónde están los cuadernos vuestros?
English: Where are your (plural) notebooks?