Then how about translating it as "what will it be" ? This is still something that would be used in English, and it would help us undertand the Finnish sentence. More generally, I see this as the weakest point in an otherwise very well done and very fun course - it seems like here and there you can't resist the temptation of throwing in the odd "guidebook phrase" that "teaches" us to say something without understanding what we're saying.
It is normal in Australia, and everybody understands it. Besides, it's literal, so I think it's perfectly appropriate. In the US there is no equivalent. We just say hello or hi (or good morning, afternoon, evening as appropriate), so none of our expressions are appropriate.