Your Stats Overview is just a basic snapshot of the overall metrics and performance of this marketing plan.  If you click on the Statistics button on the top right corner of your planning canvas it will bring up your Stats Overview.

Here you can see your overall Total Visitor flow, how many Leads you've gotten, and your Total Sales (Product Sales, Upsells, Downsells). If you would like to see a more detailed overview of all of your projects combined you may reference to the Dashboard. your Average Visitor Value, Average Lead Value, Average Transaction Value (2 Product Sales + 1 Upsell + 1 Downsell purchase to the same Unique Buyer = 1 Transaction), Total Expenses and your Overall Total Revenue.  This is a great tool to see in one click how your overall marketing efforts are performing!  To see more specific data with information funneled down to your specific Ad Sets you will want to review the Stats Table section in Live Analytics.