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 First Order has caught up with Poe's X-wing squadron! Agent Terrex has them boxed into a corner! Then...the egg starts to hatch.