The following table shows the possessive pronouns in Spanish.
|his, her, its, yours||suyo|
The possessive pronouns change their number and gender together with the thing that is possessed. They do not change their number and gender together with the possessor.
|Your hair is short. Mine is longer than yours.||Tu cabello es corto. El mío es más largo que el tuyo.|
|The words are his. They are not mine.||Las palabras son suyas. No son mías.|
|What is ours is yours.||Lo nuestro es vuestro.|
|The dogs are theirs.||Las perras son suyas.|
Since suyo can refer to many different persons, you can disambiguate it by using de + person instead.
|The book is hers.||El libro es de ella.|