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.
In a galaxy linked together by a newly formed Republic and protected by the Jedi Knights, two fortune-seeking hyperspace explorers unwittingly ignite a war between the previously uncharted Sith Empire and the Republic, the repercussions of which will echo for a thousand years afterward, and change the lives of young Jedi Ulic Qel-Droma and Nomi Sunrider forever!