het vertrek
het-worddeparture
/ɦɛt vərˈtrɛk/
de vertrekken
This one you just learn — no rule points to het here.
Het vertrek van de trein is om tien uur.
The departure of the train is at ten o'clock.
The de/het checker covers one word. The full platform covers vocabulary, grammar and all five DUO sections.