"Det er professionelt arbejde."
Translation:It is professional work.
That would translate into "That is a professional work", which sounds pretty odd to me. With det, you already specified which work you meant, so there is no need for the et, at least I see it like this
Policemen say that all the time while they stare at a corpse in black movies...
Does it mean that this work has been done perfect or that this work's been done by professional (which is pretty the same but i would say there's the difference) or that this work can be done only by professional?
And does "arbejde" is being used in the meaning of "piece of work"?