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.
When many on his home planet of Cerea clamor for the advanced technologies of other civilzations, Jedi knight Ki-Adi-Mundi opposes this change, and retribution comes in the form of false accusations of murder.