Deal Flow
Venture capitalists make deals. That's what they do. They receive offers to invest in businesses, sort through the offers to suss out the most promising ideas and then put money into the best situations they can find. Lots of back-slapping. Lots of love thrown out there to generate love back in the form of young entrepreneurs asking for money.
Deal flow describes the rate at which investors review these deal proposals. Think of it like a sports stat. In basketball, you might see field goal percentage or three-point percentage, the rate at which the player makes certain kinds of shots. Or in baseball, you might see on-base percentage, the rate at which they get on base. Or in football, a quarterback might have a completion percentage, the rate at which their passes get caught. That's a stat series on performance-flow.
If you were running a venture capitalist fantasy league, you'd definitely check out each person's deal flow before your draft. It's a sign that big-shot Wall Street or Silicon Valley types are looking at deals...basically, that they are working.