This is the 2422nd most frequent Portuguese word.
aquelas
"Those" (feminine plural).
Here 'aquelas' is used as a demonstrative pronoun to describe feminine plural nouns in a distal manner, indicating objects far from the speaker.
Aquelas flores no jardim são lindas.
Those flowers in the garden are beautiful.
In this sentence, 'aquelas' is used after the preposition 'de,' again serving as a demonstrative pronoun referring to feminine plural nouns distal from the speaker in space or time.
Eu me lembro de aquelas tardes na praia.
I remember those afternoons at the beach.
Here 'aquelas' functions as a demonstrative pronoun specifying feminine plural nouns located far from the speaker's immediate surroundings.