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.
Kanan Jarrus is a valued member of the Ghost crew from the show Star Wars Rebels. His backstory is a fascinating one that’s been explained to a certain extent (like the fact that his name before Order 66 was Caleb Dume), but a lot of it was still left somewhat of a mystery. This comic series gives fans more of his origins as a Jedi Padawan.
Caleb Dume was Padawan to Master Depa Billaba to whom he idolized greatly and felt at peace with. After losing his master to Order 66, Caleb must learn how to survive the aftermath of the purge without the Jedi Order to guide him. He starts by changing his name to Kanan Jarrus to hide his identity before accepting his new life.
In Star Wars: Rebels, Kanan Jarrus is a cocky, sarcastic renegade fighting the Galactic Empire alongside the ragtag crew of the Ghost. But years before, during the Clone Wars, he was known as Caleb Dume, a Jedi Padawan training under Master Depa Billaba. Neither master nor apprentice ever suspected that their "loyal" Clone Troopers would turn on them upon the issuing of Order 66 — the Emperor's directive to execute all Jedi. How did Caleb Dume escape the Jedi purge? How did he learn to survive on his own after his master fell? And how did he become the man we know as Kanan Jarrus? What can a Padawan do when being a Jedi makes him a target? Join young Caleb for a tale that bridges the years between the Clone Wars and Rebels! Collecting KANAN: THE LAST PADAWAN #1–6.