As an adjective
The translations ese and aquel agree in number and gender with the nouns they modify; that is translated by ese, esa, aquel, aquella, and those by esos, esas, aquellos, aquellas, depending on the meaning being translated, and what follows:
- that book/magazine = ese libro/esa revista or aquel libro/aquella revista
- those books/magazines = esos libros/esas revistas or aquellos libros/aquellas revistas
As a pronoun
Again, the translations ése and aquél agree in number and gender with the nouns they are standing for; that is translated by ése, ésa, aquél, aquélla, and those by ésos, ésas, aquéllos, aquéllas, depending on the meaning being translated, and what is being referred to:
- that (one) is yours = ése or aquél es el tuyo
- those were the best years of my life = ésos or aquéllos fueron los mejores años de mi vida
▪ When that as a pronoun is used to refer to something which is not specified for gender, it is translated by the neuter eso or aquello, according to context:
- what’s that? = ¿qué es eso?
- why did he do that? = ¿por qué hizo eso?
- what’s that over there? = ¿qué es aquello que se ve allá?
Sometimes it is not translated at all:
- that’s incredible! = ¡es increíble!
For more examples and particular usages see the entries for that