Ce livre est le mien.
English: This book is mine.
Possessive pronouns in French replace a noun and show who owns something. They agree with the gender and number of the noun they replace.
Use French possessive pronouns to avoid repeating a noun and to show possession. They replace a noun that has already been mentioned or is clear from the context.
Ce livre est le mien.
English: This book is mine.
Voici ta chaise et voilà la mienne.
English: Here is your chair and there is mine.
Leurs enfants jouent avec les nôtres.
English: Their children are playing with ours.
Ta voiture est rouge, la sienne est bleue.
English: Your car is red, hers/his is blue.
Nos idées sont différentes des vôtres.
English: Our ideas are different from yours.