The adverb amiably describes something you do in a friendly way, like when you chat amiably with your neighbor when you're both out walking your dogs.
The Latin root of amiably is amicabilis, or "friendly," which in turn comes from the Latin word for "friend," amicus. When you speak amiably, you talk the way you would to a friend — cheerfully, genially and relaxed. Doing something amiably means you have a good attitude toward whatever it is; you enjoy the company of the people who are also there.