Definition from Wiktionary, the free dictionary
A reference to the literal bottom line of an income statement or other accounting record.
- (accounting) The final balance; the amount of money or profit left after everything has been tallied.
- (idiomatic, uncountable) The summary or result; the most important information; the upshot; the net-net.
- The bottom line is that there simply are not enough hours in the day to finish all there is to do.
Derived terms 
Usage notes 
When somebody talks about increasing the bottom line, it means doing things to either increase the revenue or decrease expenses so the net income increases.