"Bebo is the protagonist of the film and she has a very good part in it. But it is also a beautiful love story about what happens to two characters from the same line of work and how much misunderstanding is created by people who are supposed to make that communication easier," the 39-year-old actor said at an event here.
Kareena plays an actress who touches the heights of fame and then falls from glory.
Asked about his role, Arjun said: "It's going to be a Madhur Bhandarkar film which deals with a lot of layers of reality and that's what I enjoy doing. I like all my characters to have a certain level of realism. I hope to portray it with conviction and not in a caricaturist manner."
Arjun debuted in Bollywood with 2001 movie "Pyaar, Ishq Aur Mohabbat" but had to wait for a long time to find a firm foothold. He was first appreciated for his role in "Don - The Chase Begins" (2006) and then people liked him in the negative role in "Om Shanti Om". But he came into his own as a brooding musician in "Rock On!!" and continued it with "Raajneeti".
"Heroine" is expected to hit theatres September this year.