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.
Imperial troops are bombarding the planet of Delrakkin—disguised as Rebel forces! The Empire wants the Rebel Alliance to be blamed for the attack. The Rebels must stop this evil deception. Your mission: to defend Delrakkin…and save the Rebellion.