Complex sentence: She bluffs her way into the DEA office by posing as a delivery girl, only to be ambushed by Stansfield in a bathroom; one of his men arrives and announces that Léon had just killed one of the corrupt DEA agents in Chinatown that morning.
Split into simpler sentences: She bluffs her way into the DEA office by posing as a delivery girl, only to be ambushed by Stansfield in a bathroom. Mathilda learns from Stansfield that Léon killed one of the corrupt DEA agents in Chinatown that morning.