Cash flow is essentially the movement of money into and out of your business; it's the cycle of cash inflows and cash outflows that determine your business' solvency. (About.com: small business)

Preparing a monthly cash flow forecast provides you with the opportunity to show dollar figures, representing revenues and expenses, in the month the business expects to collect and spend the cash. (Canada business)

The difference between the cash in- and out-flows within a given period indicates the net cash flow. When this net cash flow is added to or subtracted from opening bank balances, any likely short-term bank funding requirements can be ascertained. (Planware.org)