This is the 582nd most frequent Catalan word.
aquelles
"Those" (feminine plural).
Here, 'aquelles' is used as a demonstrative adjective describing the noun 'muntanyes' to specify that these particular mountains are being referred to from a distance.
Aquelles muntanyes són molt altes.
Those mountains are very tall.
'Aquelles' again serves as a demonstrative adjective referring to 'paraules', indicating specific words previously mentioned or implied, also denoting distance.
No recordo aquelles paraules exactament.
I don't remember those words exactly.
In this sentence, 'aquelles' functions as a demonstrative adjective modifying 'antigues fàbriques', emphasizing the reference to particular factories far or distant in context.