Demonstratives are words that indicate a subject already understood by the speaker and listened. In English, these are words like “this” and “that”.

Portuguese demonstratives must agree with the gender and plurality of the subject:

   aquele tempo
   that time

   aquellas horas
   those hours

To simplify things somewhat though, they take the same form whether being used as a pronoun or adjective:

   Pronoun
   Esta é minha amiga.
   This is my friend.

   Adjective
   Essa amiga sua é linda.
   That friend of yours is pretty.

One aspect of Portuguese demonstratives that is difficult to learn is that esse (and the other ess~ words) can translate as both “this” and “that”. Portuguese speakers often don’t make the same distinction we would based on the physical location of the subject. As you listen to more Portuguese speakers in conversation you’ll learn the natural cases for each word’s use.