"That is a coat."
Translation:Dat is een jas.
I think it's because a vest doesn't have sleeves or is short. https://www.vandale.nl/gratis-woordenboek/nederlands-engels/vertaling/Vest#.W3DdFagaU0M
But I think in Vlaanderen they use vest to refer to a jacket/coat (jas), and jas to refer to a longer coat, like a raincoat or something of the sort.
Hope this helps!