hit it off (with someone)
To quickly become good friends with someone.
Eg. Look how John hit it off with Mary. Yes, they really hit it off.
So how did it go with Beth?
Great! I took her to dinner and we totally hit it off.
Great! I took her to dinner and we totally hit it off.
Despite the 12-year difference in their ages they hit it off instantly.
Smart Up Your English 
This expression is similar TO get on WITH?
Exactly! The difference is that if you “hit it off with somebody” you are talking about the fact that you immediately get on with them, right from the word go.
thanks,i will put in my vocabulary