The experiments page shows you the variations of the site that have been tested or are currently running. You are able to toggle between the various devices to see the performance of each. You can also change the date range to specify the time period you want to see.
Each color on the graph represents a different variation that is running and the volume of traffic that is going to each. For example, if the graph is mainly one color, it means that a single variation is winning the majority of the traffic.