TinkerBell053,
The Bellvue Lounge is the same thing as the Bellvue Bar at the Boardwalk. It's basically the "lobby bar" of the resort, but is much nicer that what you'd expect for a lobby bar. The Bellvue is located to the right, tucked into a nice little niche, just as you enter the resort's main lobby. This area is normally an open area for regular Guests, but for private parties I think they can "rope off" the entrance so it becomes "semi-private" and regular Guests don't disturb you.
There is a small bar, with cozy seating areas inside (no room for sit-down tables though), and a beautiful covered patio outside that overlooks the BoardWalk. I believe they can set up the F&B and tables outside, which would be really nice (but again, probably only for a small group of like 30 ppl max).
I don't know if you can use this area for a full wedding reception or if they just use it for things like cocktail/finger food receptions, etc. The best bet is to ask your EM to check on this.
Good luck,
RubySlipperGirl