1.
When you come on to a particular topic, you start discussing it.
We’re now looking at a smaller system but I’ll come on to that later.
PHRASAL VERB : V P P n
2.
If someone comes on to you, they show that they are interested in starting a sexual relationship with you. ( INFORMAL )
I don’t think that a woman, by using make-up, is trying to come on to a man.
PHRASAL VERB : V P P n