Operating cash flow, usually more formally described in accounts as "cash inflow from operating activities", is the amount of actual cash made by a company's business. It is similar to operating profit but without the non-cash items and accruals.
A reconciliation of operating profit and operating cash flow is always included in the full year results, and usually in half yearly and quarterly results. This is worth looking at as it (hopefully) explains any differences between the profits and cash flow. Profits are ultimately useless unless converted into cash and looking at the reconciliation may highlight problems.
The usual non-cash items are fairly obvious — depreciation and amortisation and changes in working capital.
Adding back deprecation and amortisation are the adjustments that are made when calculating EBITDA from operating profit. This is why EBITDA is often regarded as a cash flow measure. It is the same as operating cash flow without the working capital adjustments, which are volatile and often obscure trends and changes. EBITDA is also usually calculated before exceptional items, which again gives a clearer view of underlying trends.
Ultimately, cash flow is what is what matters to investors, however operating cash flow, while important, is only part of this and investors need to look at the cash flow statement as a whole. It is also useful to look at measures of cash returns to investors. Operating cashflow can be a useful measure, as can EBITDA and free cash flow.