In both Spanish and English demonstrative adjectives modify nouns. In English they are this, that, these and those. In Spanish they are este, ese and aquel. When translated, the similarities are obvious:
Este(a) = This
Esto(a)s = These
Ese(a) = That
Eso(a)s = Those
Aquel(la) = That over there
Aquello(a)s = Those over there
Hope this helps.