What does Chart Advisor do? To quote one of the Program Manager's of the Microsoft Excel team, Scott Ruble: "The Chart Advisor intelligently suggests different chart types based on an analysis of your data in Excel 2007."
To install the plug-in, first you must download it here and then run the installer. The next time you boot up Excel you should see the new Chart Advisor icon located in the "Insert" tab. Simply click the icon to run the plug-in.
Since this is a plugin, you have to see it to fully grasp it. Take a look at the video below on how Chart Advisor works.