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.
Rey has been captured by the evil First Order! Meanwhile, Finn plans a mission with the Resistance in order to save Rey and destroy Starkiller Base! Only the vicious Kylo Ren stands in their way…