This is the 48th most frequent Catalan word.
primera
"Primera" means "first" in English.
Here, 'primera' is used as an ordinal adjective modifying 'vegada' (time) to denote the sequence of events.
És la primera vegada que visito aquesta ciutat.
It's the first time I visit this city.
In this sentence, 'primer' is the masculine form of 'primera' since it modifies the masculine noun 'capítol'.
Vaig llegir el primer capítol del llibre ahir a la nit.
I read the first chapter of the book last night.
'Primer lloc' refers to the first place in a sequence, with 'primer' properly declining for the masculine noun 'lloc'.