Possessive Pronouns
| SINGULAR | ||
| MASCULINE | FEMININE | English |
| le mien | la mienne | mine |
| le tien | la tienne | yours |
| le sien | la sienne | his/hers/its |
| le nôtre | la nôtre | ours |
| le vôtre | la vôtre | yours |
| le leur | la leur | theirs |
| PLURAL | ||
| MASCULINE | FEMININE | English |
| les miens | les miennes | mine |
| les tiens | les tiennes | yours |
| les siens | les siennes | his/hers/its |
| les nôtres | les nôtres | ours |
| les vôtres | les vôtres | yours |
| les leurs | les leurs | theirs |
The possessive pronoun agrees in gender and number with the noun it refers to, not with the owner.
This is Paul's book. This book is his.
This is Sophie's book. This book is hers.
C'est le livre de Paul. C'est le sien.
C'est le livre de Sophie. C'est le sien.
Note that the adjective used in English is 'his' or 'hers' depending on the gender of the owner, male or female.
But in French, the pronoun depends on the gender of the noun it applies to, whether the noun is masculine or feminine.
As the word 'livre' is masculine (un livre), the adjective that should be used is the masculine form 'le sien' no matter the gender of the owner.