this song refers two the tragic stories of 2 pairs of lovers: Ranjha-Heer and Mirza-Saahiba. Ranjha left Heer to marry another girl while Mirza took Saahiba away on a horse..... So the character here in the movie who is named as Heer says that she wants to be known as Saahiba not Heer. Though Saahiba and Mirza die tragically