It opens the stats/macro tracking page tied to your subscription, letting you see nutrition totals from the meals in your plan. It only appears as a "Macro Tracking" link under the My Subscription menu group for accounts on the Pro/Enterprise plan (or with the Macros override on), with both the Macros and Subscriptions modules active, and both the global "Show Macro Nutrition" setting and the "Show Macro Tracking on Profile" setting (Config, tab "Order: Subscription") turned on.