Complex sentence: Lily pulls aside Claire, a woman at the bar, warning her of Barney's villainy, and she sits down with the rest of the gang as they explain the events that lead up to that night.
Split into simpler sentences: Lily pulls aside a woman at the bar, warning her of Barney's villainy. The woman (Claire) sits down with the rest of the gang as they explain the events that lead up to that night.