This is the 747th most frequent Slovak word.
trvá
"Trvá" means "lasts" or "continues" in English.
Here, 'trvá' refers to the duration of an event or activity, specifically the length of the train ride.
Cesta vlakom do Bratislavy trvá dve hodiny.
The train ride to Bratislava takes two hours.
In this sentence, 'trvá' indicates the time until which an event continues, in this case, a lecture.
Prednáška trvá do štvrtej hodiny popoludní.
The lecture lasts until four in the afternoon.
'Trvala', a conjugated form of 'trvá', expresses the importance of the extended continuity of an occurrence, here referring to the discussion.