Cash flow is an accounting term that refers to the amounts of cash being received and spent by a business during a defined period of time. In the private equity and mezzanine debt world, EBITDA which is earnings before interest, taxes, depreciation and amortization, is often used as a proxy for cash flow.
It is the measure of the actual cash generated by a business rather than the accounting profit. Positive cash flow means more money is coming into the business than is leaving it. Negative cash flow is the converse. For asset intensive businesses, capital expenditures should be factored into EBITDA to determine cash flow.