분 is the polite word for 'person', and the -(으)ㄴ clause in front describes something they have done or are able to do: 0점 맞으신 분 있으세요? 'has anyone here ever got a zero?', 사투리 쓸 수 있으신 분 있으세요? 'can anyone speak the dialect?'. Note the honorific -시- inside the modifier (드셔보신, 창업하신, 가신) — you use it about the people you are asking, never about yourself. With 있잖아요 it points at someone you both know: 화장실 가신 분 있잖아요 'you know, the one who went to the loo'.