The arrows should show you, that the "Staging Farm" and the "Productiv Farm" consume from service applications of the "Service Farm". This allows to use the same taxonomies in every farm, per example. Or (and this is my favorite at the moment :-) ) to push central stored Content Typs to every Farm in your envriroment.
Chak Corner described the configuration for "Content Typ Hubs" in a blog post in detail.
Have fun by playing with service applications by yourself for the first time!