A lock-off is basically just a studio that has an adjoining door to a 1-BR. Right now, the only way to have a 2-BR unit at AKV is to have a 1-BR plus a connecting studio which counts as the second bedroom. It is called a lock-off because you can just lock off the studio portion and have a regular 1 BR.
Once Kidani Village is built, there will be dedicated 2 bedroom units.
Hope this helps.