The 'Orders' metric shows the total number of purchase events made on your site. This metric is vital for eCommerce sites in measuring conversion. You can combine this metric with any dimension to see what which dimension values contributed to an order. For example, you could see the top campaigns (using the Tracking code dimension) or top internal search terms (using an eVar ) that contributed to purchases.
How this metric is calculated
This metric counts the number of hits where purchase exists in the events variable.