This is the 955th most frequent Croatian word.
većih
"Većih" means "bigger" or "larger" in the genitive plural form.
Here, 'većih' is used in the genitive plural to describe 'prostorija', indicating they are larger.
Potreban nam je izbor većih prostorija za događaj.
We need a selection of larger rooms for the event.
In this sentence, 'većih' is the genitive plural form of 'veći', agreeing with 'kuća' and describing their larger size.
Imamo plan za gradnju većih kuća.
We have a plan to build larger houses.
In this context, 'većih' modifies 'problema', in the genitive plural, and specifies they are of a larger nature.