If you’re on the fence, you can’t decide something. You’re torn between two options. If you’re standing at the ice cream counter, not sure if you should get chocolate or vanilla, you’re on the fence.
Being on the fence means you really just can’t decide. It’s as if you’re sitting on the fence because you can’t decide which yard to play in. If you can’t decide whether to take a job or not, you’re on the fence. If you don’t know which basketball team to root for, you’re on the fence. This word is all about indecision. When you make a choice or commitment, you’re no longer on the fence.