Standard English lost the third level, so that the "that, there" series covers the ground of "yon, yonder".
The demonstrative determiners can also be used as pronouns, with the addition of the neutral singular forms esto, eso, aquello.
A similar three-way system of demonstratives is found in Portuguese, in Slavic languages, in Japanese and in Turkish.
It inflects for gender and number as follows: Thus: The usually-masculine form el is used instead of la before feminine nouns that begin with a stressed a (or rarely, au) sound (as well as, in principle, ai although such words are almost never found in practice): La is used, however, when el would imply a masculine noun: Feminine el is never used, however, before feminine adjectives that begin with a stressed a: Azúcar is a very special case.
For example: Given the ambiguous meaning of "su/s", this is often avoided, and replaced by other forms that clearly state who owns the thing in question.