At most resorts, it means it's a 1BR that attaches through an internal door to a 1BR. The 1BR side offers a king bed in the bedroom, and generally a sofa bed in the living area. There is a kitchen. The studio side will have a queen bed and a sofa bed.
There are sometimes murphy beds on the studio side, varying by resort. At OKW, the studio side is always 2 queen beds.
Studio side - 1QN, sleeper sofa, wet bar, bath, balcony or patio.
1BR side - 1k In Br, sleeper sofa, (some also have sleeper chair), bath, kitchen, W/D. Extra bath at grand Californian.
Some of the studio sides might also have a bunk sized murphy bed. So some sleep eight (AKV Value, CCV, SSR), some nine and some ten (only the lockoff two bedroom at GFV).
With a 2BR lock-off, they can lock the internal connecting door on both sides and use it as separate studio and 1 BR units. With a dedicated 2BR, there is no locking connecting door, and there is only one external door.
That OKW video is before the recent renovation. By the way, anyone who plans to take a video tour of a villa, watch the one by David's Crew of BWV. That was well done.