This is the 1672nd most frequent Turkish word.
çoğunlukla
Mostly.
In this sentence, 'çoğunlukla' is used as an adverb to indicate the frequency of the action described by the verb 'vakit geçiririm' (spend time).
Çoğunlukla evde vakit geçiririm.
I mostly spend time at home.
Here, 'çoğunlukla' specifies the common or predominant occurrence of an event, 'yağmur yağar' (rains) during a certain period.
Bu mevsimde çoğunlukla yağmur yağar.
It mostly rains in this season.
In this example, 'çoğunlukla' highlights the typical time frame during which an event, 'toplantılar yapılır' (meetings are held), occurs.