Star Wars Gives Canon Explanation For BBY & ABY

[هَـ-ђāŵĩ-ـَاوِي]

The Star Wars timeline and calendar has always been a bit confusing, but there's now a canon explanation for using BBY and ABY as its main distinction. The Star Wars timeline uses a peculiar dating system, one that resembles the real-world equivalent of BCE and CE, where a single event separated the halves of the calendar. The Star Wars version centers around the Battle of Yavin, when Luke Skywalker destroyed the Death Star in the original Star Wars, which was later retitled A New Hope. Thus, the Star Wars calendar is separated into BBY and ABY, or before and after the Battle of Yavin.
Sean Morrison

Star Wars Gives Canon Explanation For BBY & ABY

Why are Star Wars years in BBY and ABY?

screenrant.com