In Zack Snyder's Justice League.
When Flash got late for his job application.
He said: Essentially, the bus didn't come, then the bus did come.

I quite knew what "Essentially" meant, however, I looked up anyway to find.

used to emphasize the basic, fundamental, or intrinsic nature of a person or thing.

I still don't know what does it mean?
English is a funny language.