Rosendal is a town in Hordaland.
Rosendal is about 2-2,5 hours drive from Bergen, and about 2 hours drive from Haugesund. From Bergen you'll have to take one or two car ferries, depending on route.
There are buses going from Bergen to Rosendal. As this would require change of bus in most cases, and timetables on the web is mostly in Norwegian only, it may be easiest to contact the information phone 177 or a tourist information office.
By express boat
Maybe the most comfortable way to travel between Bergen and Rosendal, the express boat Rødne Fjord Cruise  have a couple of departures every weekday and one every saturday and sunday. The boat is a bit more expensive than the bus, but gives a traveller a much better view. If the view is not nice enough there is also free a wireless internet connection on board. The boat also have scheduled stops at Bergen airport on most trips.
Rosendal itself is barely a village and you can walk most places. In summer you can go by horse and carridge from the harbour to the Barony.
Rosendal is famous for having Norways only Barony . The small castle, wich dates back to 1665 is surrounded by a beautiful renaissance garden.
During the summer seaon the Barony frequently have events like concerts, theater plays, art displays, and of course guided tours around the castle and the surrounding gardens.
Note that the english version of their homepage is somewhat incomplete.
The Kvinnherad Church, is a medieval church built of stone in 1250. The church contains both artwork and the Rosenkrantz burial chamber with some beautifil sarcofagus.
The church is open for guided tours during the summer season. More info on the Barony website.
The Shipbuilding Museum
Located just by the harbour, the Shipbuilding museum is open during the summer season.
Apart from seeing the sights it's not much more to do in Rosendal itself, however the surrounding area is very nice for hiking, with beutiful mountain terrain. Several summits can be reached from footpaths that starts in Rosendal.
For more info on hiking in the area, ask staff of the place you are staying, or the tourist information office. It's a good idea to bring a map, and to make sure that you are in good enough condition for the trip you are planning. Note that many of the mountains in this area are very steep, so a short distance may take some time to cover (the view from the top however, makes it worth it!).
In Kvinnherad municipality 69 paths have beed marked and graded, so that you can choose a walk that suits you.
Rosendal is a nice base for visiting the Folgefonna Glacier. Folgefonni Breførarlag have guided tours (and you will need a guide for walking on the glacier itself. It's also possible to walk up to the glacier through the Bondhusdalen.
Note that you may have to arrange your own transport from Rosendal to Mauranger, where some of the trips start (just less than 30 minutes of driving).
Most hotels also have restaurants open to people not staying at the hotel.