Shadow coffee is coffee grown under a shade canopy (shade provided by mixed native trees). Arabica coffee is traditionally grown in shade in many (but not all) parts of Mexico, Central America, Colombia, Peru, and Venezuela, and in some other parts of the world, including India and some regions of Indonesia and Africa. Elsewhere arabica coffee is traditionally grown in full sun, or near full sun.
As these shade canopies provide a habitat for migrating song birds in Central America, coffees grown under such a native canopy is sometimes marketed as "bird friendly."
Shade grown coffees most definitely are much easier on the environment than sun grown coffees, and the better tasting Central American coffees are best grown in shade.