This is the 3307th most frequent Polish word.
trwać
To last; to endure; to persist.
Here, 'trwać' is used in the noun form 'trwania', referring to the time span of something.
Czas trwania kursu to trzy miesiące.
The duration of the course is three months.
In this sentence, 'trwać' is used in the past tense, describing the length of an event.
Koncert trwał trzy godziny.
The concert lasted three hours.
'Trwać' is utilized in the future tense here, indicating the anticipated duration of an activity.