A possessive pronoun replaces a noun preceded by a possessive determiner like mi, tu, su, etc. This noun being replaced is called the antecedent. The following sentence has an example of a noun with a possessive determiner, su acento and later a possessive pronoun el mío, which replaces what would have been mi acento.Ellos tienen su acento mexicano, pero el mío, como que no sé, no se acerca tanto al de ellos.
They have their Mexican accent but mine, like I don’t know, isn’t as close to theirs.
In Spanish, possessive pronouns indicate the possessor (me, you, them, etc.) and it must agree in number and gender with the antecedent. They are generally preceded by a definite article, which also agrees in number and gender with the antecedent. In the following example the feminine singular determiner la and pronounmía are used because the noun being replaced, casa, is feminine singular.
I stayed at her house and she stayed at mine.
Depending on the context, suyo, suya, suyos, suyas may mean his, hers, yours (for singular and formal you), or its.