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.
The Junior Jedi Knights concludes with Anakin taking his leap toward Jedi Knighthood. He's contrasted with Uldiir, a student weak with the Force who steals a Jedi Holocron and Obi-Wan Kenobi's lightsaber, thinking he can shortcut his path to becoming a Jedi. Anakin must follow in his uncle's footsteps in redeeming a lost Jedi in order to become one himself.
When Anakin's classmate and aspiring Jedi Uldir fears he is not learning fast enough, the discouraged youngster steals the Holocron, a powerful and ancient Jedi treasure, and Obi-Wan's lightsaber.