BBY/ABY is used to position items along the Star Wars Timeline. BBY refers to Before the Battle of Yavin. ABY refers to After the Battle of Yavin. The Battle of Yavin in Episode IV: A New Hope occured in 0 BBY/ABY.
Han has a traitor to the Rebellion on board the Falcon! But can he figure out who it is before they get him killed? And more importantly… can he stay in the Dragon Void race?!?