Revenue Growth Rate is an indicator of how well a company is able to grow its sales revenue over a given time period. While the revenue is an actual number, the revenue growth rates simply compares the current sales figures (total revenue) with a previous period (typically quarter to quarter or year to year).
This provides an indicator that allows easier comparisons between different firms (especially in the same industries or markets) and provides a measure of the extent to which a company is able to grow.
Revenue Growth Rate = Revenue this period / revenue previous period
This indicator will be included in my book: Key Performance Indicators - the 100 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 actual usage.