what does it mean this "to get on the bell"
I've never heard it. Where did you hear or read it?
We do have "on the ball" - be on the ball, get on the ball. It's an idiom that means be alert, pay attention. I suppose it comes from the expression: "Keep your eye on the ball," which means: focus on what's important - as a good ball player does.
[I am a copy editor and have tutored university students in writing.]