1. go on something: to base an opinion or decision on something.

Since there were no witnesses, the police had little to go on.

2. Go on/ go on about/ go on and on (about something): to talk so much that people become bored or annoyed.

You do go on, don’t you?

Oh how he can go on and on about how smart he is.

My mother can go on and on about how my generation is lost.

3. Go on: to go to a place before someone else who you are with.

Why don’t you go on without me?

4. Go on: to walk onto a stage to begin your part in a performance.

I go on in the middle of the final act.

5. going on (for) something: almost a particular age, time, or amount.

It’s eight, going on nine.