In finance, the net is the total after you have cancelled positive values against negative values. For example, if you took in $30 and paid out $20, then your net is $10.
In Microspeak, this term has moved into project planning and has undergone redoubling, so it's not just net; it's net net. The doubling of the word was probably added to create a sense of impatience. Here's an imaginary conversation that illustrates the term:
Speaker 1: We're five days over on component X, but component Y is ahead of schedule, and we can have some of them h...
Speaker 2: (interrupting) What's the net net?
Speaker 1: Um, we're two days behind.
The net net is not a real estate transaction but rather is a short summary of a complicated situation, what often goes by the term bottom line.
Here is an actual citation:
(At the top of a long email message)
Net net, we're delaying the release we had planned for tomorrow to try and get some critical fixes in.
Another use of the term net net is to highlight a conclusion from a lot of data.
(at the bottom of a large information-dense PowerPoint slide)
Net Net: Eliminate XYZ from our target set.
Both senses of net net highlight the principle of I know you're impatient, so I'll cut to the chase.