From the page: "The success of your employees equals the success of your business. You must retain your best talent and grow their skills to achieve and maintain your competitive edge in the rapidly changing marketplace. To ensure employee success, have a solid, trusted performance management process in place."
Think that's a lot of information for something labeled as "easy ROI"? Trust me, it's easier than it sounds. Once you get the hang of it, ROI on Facebook Ads will take you next to no time to calculate.