C'est mon livre.
English: This is my book.
Possessive adjectives in French are words used before a noun to show who owns or is connected to something. They change depending on the gender and number of the noun that follows.
Use French possessive adjectives to say who something belongs to, or to show relationships. They always come before the noun, and must match the noun in gender (masculine/feminine) and number (singular/plural).
C'est mon livre.
English: This is my book.
Voici sa maison.
English: Here is his/her house.
Nos amis arrivent.
English: Our friends are coming.
Leur voiture est rouge.
English: Their car is red.
Tes idées sont intéressantes.
English: Your ideas are interesting.