Operating Cash Flow is the total cash generated from the operations of a company
Operating Cash Flow (alternately "Cash Flow from Operating Activities", or "Cash Flow from Operations") is a measure (listed on the Cash Flow Statement) of the total cash generated from a company's operations. Though there are several ways to perform the actual calculation, most start with the net income (from the income statement), add depreciation, and adjust for changes in working capital (e.g. changes in liabilities, inventories, accounts receivable etc.).
Operating Cash Flow tells how much cash a company has been able to generate from the operations of its business. Since it adjusts for liabilities, receivables, and depreciation it is a more accurate measure of how much cash a company has generated (or used) than measures of profitability such as net income. As such, a massive and/or unexpected discrepancy between the net income and operating cash flow of a company could be indicative of disproportionate non-cash income. For example: A company with a lot of machinery (fixed assets) may have low net income due to depreciation; however the company does not pay for depreciation with cash, and, assuming everything else remains the same, the operating cash flow for the company would be higher than its net income.
The management has far less discretion over the cash flow statement than it does over the income statement -- as a result some investors may find it to be a better reflection of reality than the income statement. Also, given that companies require cash to run its everyday operations, cash flow from operations are likely to highlight any liquidity issues that a company might have.
Rogers Widget company had net income of $500 in 2008. The company has a capital extensive business (think lots of big heavy machinery) and in 2008 it had depreciation expense of $300. Since depreciation doesn't actually require that the company pay out anything in cash, the company has to add back this expense in order to come up with operating cash flow. In 2008, the company generated $800 in cash flow from operations.