hold on (wait),
1. Used alone to tell someone to stop doing something (which usually involves trying to get your attention) and to wait until you are ready to attend to them. English = 'Hold on!', 'Hang on!', 'Wait a sec!' and so on.
1. Used to introduce a statement which contrasts with what you have just said. English = but, yet, though, although.
2. Used alone to show the person you are talking to that you are thinking and about to say something. English = umm, err.