@Laura2592 so you'll have lots of time. I don't really know the area around Copenhagen very well, but my favourites in Denmark are Ribe, in the southern part as well as the nature around it. If its in season I recommend doing an oyster safari, that is an incredible experience, whether you like oysters or not.
On Fyn there's a wonderful castle called Egeskov, but Denmark has a lot of castles. I've not been able to visit many of them so I can't really recommend any. Many have been converted to conference venues and hotels.
We live in the northern part of Denmark which is mostly known for its nature - Skagen, Løkken, Lønstrup, Rudbjerg Knude are all must sees if you come all the way up to the north. Northern Denmark was historically poorer, so less castles - though there is Dronninglund and Voerborg castle if that's interesting.
Denmark is famous for its beaches, especially here in the North, with Løkken being the most famous one with its small beach houses, surfing and a beach that goes for miles.
Denmark is not known for wines, but there's lots of good food. Noma is the most famous place, but there are lots of good places to eat and try local food, depending on the region you plan to visit.
Happy to help with more specifics where I can, or provide links etc.