The possessive adjectives in French indicate that something belongs to someone. For example: my pen, her house, our school.In French they are as follows:My: mon, ma, mesYour (singular): ton, ta, tesHis/Her/Its: son, sa, sesOur: notre, notre, nosYour (plural): votre, votre, vosTheir: leur, leur, leursFor example: mon stylo, sa maison, notre écoleTo decide which one to use, you look at the gender and number of the noun you are describing. For example, you use mon for stylo because stylo is masculine and singular. If I wanted to say "my pens", I would use mes stylos. The gender you choose matches the noun you are describing (the pens, the house, the school etc) and NOT the person to whom the pens, house, school etc belong. For example, Her house - sa maisonHis house - sa maisonHouse is a feminine noun so will take the feminine possessive adjective.