This is the 4th most frequent Lithuanian word.
buvo
"Buvo" means "was" or "were" in English.
The word 'buvo' is used here as the past tense of the verb 'to be', describing a state of warmth that occurred in the past.
Vakar buvo šilta.
Yesterday it was warm.
In this sentence, 'buvo' indicates a past situation or condition, specifically describing the time at which the leaving needed to happen.
Buvo metas išeiti.
It was time to leave.
Here, 'buvo' expresses a past emotion or state experienced by the subject, in this case, happiness.