In a normal company (as in not a startup) you'll work 8 to 16 year round and have at least 5 weeks of vacation, most of them usually to be spent during the common vacation time (Fellesferien) which is in july.

If you're lucky you can expect at a good chunk of extra days days of in may when we celebrate different christian days and of course constitution day on the 17th.

Oh, and at easter you'll have 3 days of. Most people (at least families) take the whole easter week of. Working in the government you'll often find a concept of summer time, where you work from 8 to 15 from around may to sometime in august. Those hours are to be worked extra during the rest of the year though.