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.
After leaving the Imperial Navy, a young Han Solo seeks adventure by joining a gang of galactic mercenaries - and soon meets notorious gambler Lando Calrissian and a 196-year-old Wookiee named Chewbacca! Witness Han's first flight in the Millennium Falcon - and join him on the legendary Kessel Run! But can even the fastest ship in the galaxy help Han accomplish an impossible heist for ruthless gangster Dryden Vos? There's more to this story than you saw in any theater!