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.
long and short of it, the
The substance or gist of something, as in The first page of this report will give you the long and short of it. This expression, originally stated as the short and long of it, dates from about 1500, the present order being established by the end of the 1600s.