After this overview, you get down to writing your activities and achievements. So much has been said about accomplishments that some people have been led to believe that your work experience should be one long statement of quantified accomplishments. Ideally, you'll describe what you did and how this had an effect on the business. Whenever possible, relate what you did to how what you did had an positive impact on customers or internal processes. There is nothing inherently advantageous about quantification.
Specifics sell, and quantification is one way to communicate specifics.
It's not the only way, but a couple quantified points under any employment section is always helpful. If the work you're describing is very similar to what you're looking to do next, you'll probably want to be very specific and detailed in your description. For example, let's say you managed your own one-person photography studio for the last five years. But maybe you've had enough of photography and want to take the management skills you developed into another business. Or, maybe you want to stay in photography, but not as a studio manager.