Well, we could say that good are feelings, virtues and attributes encapsulated in human’s minds and they can change intensity base on the circumstances. Thanks to this tool we all develop a sense of morality to help us maintain relations among humans, expand our social lives, and help each other.
Examples:
Officer buys food for a homeless
Driver stops on the middle of street and helps an elderly woman cross the street
Estranger gives money to a child to buy a bicycle after hearing that was stolen
Estranger lives note on car after hitting back bumper letting the owner know that he will pay for all the damages
Estranger pays for family dinner after over hearing that a family