This is the 906th most frequent Finnish word.
päivinä
"Päivinä" means "on days" in English.
The word 'päivinä' here is used in its plural form with the inessive case to indicate 'on' during certain days.
Aurinkoisina päivinä menemme usein puistoon.
On sunny days, we often go to the park.
The word 'päivinä' here is plural and implies a sense of 'on some days', indicating specific though unspecified days.
Jotkut päivinä tunnen itseni erityisen energiseksi.
On some days, I feel particularly energetic.
The word 'päivinä' here is modified by an adjective and communicates the circumstances prevailing during certain days.