This is the 1477th most frequent Dutch word.
vaak
Often.
Here, 'vaak' is used as an adverb to indicate regularity or frequency of the action
Ik ga vaak wandelen in het park.
I often go for a walk in the park.
In this sentence, 'vaak' describes the frequency of the subject's feeling.
Zij voelt zich vaak moe na het werk.
She often feels tired after work.
'Vaak' is used to describe how commonly the situation occurs.