If a theatre performance is off-broadway, that means that the production isn't playing in broadway. This can mean it is playing at a low level theatre and is just starting out. A lot of famous broadway performances start off-broadway, and work up to play at broadway.
It could be that it holds mainly new shows or touring shows and that its not on Broadway street (or apart of one of the NYC theaters). Also it could just be a low grade theater/it's in a city center.
