Revenue (also referred to as turnover or sales) is simply the income that a company receives from its normal business activities, usually the sale of goods and or services.
In accounting terms revenue represents the "top line," to denote how it is reported on an income statement (at the very top). The "bottom line," denotes net profit (what is left from the revenues once all expenses are deducted).
Generally revenue might be understood as income received by an organization in the form of cash or cash equivalents. However sales revenue can be described as income received from selling goods or services over a given period of time.
Total Revenue = Price of goods or services x Quantity sold
This indicator is included in the book: Key Performance Indicators - the 75+ measures every manager needs to know, which contains an in-depth description of this KPI, as well as practical advice on data collection, calculations, target setting, and acutal usage.