This / that / these / those
Demonstrative determiners are mostly used to specify or designate people, animals or things based on their proximity or remoteness taking into account the speaker's position
THIS
It is used when we talk about a single element that is a short distance from the speaker.
(Esto/e/a)
EX. This vase is very expensive.
Este jarrón es muy caro.
THAT
It is used when we talk about a single element that is at a certain distance from the speaker.
(Eso/e/a, aquel, aquello/a)
EX. That boy is my cousin.
Aquel chico es mi primo.
The demonstrative determiners in English do not distinguish between gender (masculine / feminine) but number (singular / plural).
THESE
It is used when we talk about more than one element that is a short distance from the speaker.
(Estos/as)
EX. These shoes are old.
Estos zapatos son viejos.
THOSE
It is used when we talk about more than one element that is at a certain distance from the speaker.
(Esos/as, aquellos/as)
EX. Those toys are dirty.
Esos juguetes están sucios.