the long and (the) short of it
The main idea or facts of something. That's the long and the short of it. If you want more details, you'll have to ask Laura. The long and short of it is that Kyle is quitting, so we need to fill his position fast.
the long and (the) ˈshort of it
used to say what the basic facts of a situation are: The examiners discussed your paper for at least an hour, but I’m afraid the long and the short of it is that you have failed.