We use Spanish possessive pronouns to talk about who something belongs to. For example, “this is mine,” “it is his,” and so on. They are not to be confused with possessive adjectives, which are followed by the noun (“it was his book,” “this is my car,” etc.).
In Spanish, the possessive pronoun is usually preceded by the definite article (the). Think of it as the pronoun replacing the noun, which would have been preceded by an article. The only time you don’t use le, la, les, las in front of a possessive pronoun is when it follows the verb ser. Each possessive pronouns must agree in gender and number to the noun they replace.
Let’s take a look at some examples:
This free is mine. This book is mine. I do not like my plate. I prefer yours. I do not like my dish. I prefer yours.