This is the 851st most frequent Ukrainian word.
сталася
"Stалася" means "happened" or "occurred."
In this sentence, 'сталася' (happened) is used to indicate the occurrence of an event, here being an accident.
Вчора сталася аварія на дорозі.
Yesterday, an accident happened on the road.
'сталася' here again means 'happened', emphasizing the time frame of the event in descriptor terms.
Ця радісна подія сталася у літню пору.
This joyful event happened during the summer season.
Here, 'сталося' is used in a question to inquire about the occurrence or detail of an event.