To concur, or to come to a mutual agreement with a person in conversation. To accept. To roll with. A friendly greeting as well as goodbye.
Chemono can also be used in suggesting something to someone as a way to ask if they agree, or it can be a way of yielding to an idea contrary to your own.
Guy 1: Right or left?
Guy 2: Left.
Guy 1: Chemono.
Guy 3: Lets not go to the movies... Chemono?
Guy 4: Chemono. Lets go to the park instead.