Complex sentence: He is interrupted when he hears his neighbour Penny (Keira Knightly) crying on the fire escape outside: she has kicked her boyfriend out because he made her miss an opportunity of going to England to see her family one last time.
Split into simpler sentences: He is interrupted when he hears his neighbour Penny (Keira Knightly) crying on the fire escape. She admits that she has just kicked her boyfriend out because he made her miss an opportunity to go to England to see her family one last time.