Well, the song is yet to come but since there are requests on the title itself, with so much hype being created around the song, here is the meaning of the phrase.
The line goes 'Chhod ke Saleem ki gali, Anarkali Disco chali.' Which literally means, leaving the street of Salim, Anarkali goes to disco.
Basically the sense here is that a Anarkali, who was a lover of Prince Salim, leaves him (and with that, the traditional 'love') to go to a disco, which is a symbol of modernism here.
The song, composed by Sajid-Wajid, and sung by Mamta Sharma, features Malaika Arora Khan, along with Boman Irani, Akshay Kumar and John Abraham.