A person can be a hero by having inner strength, and a resolve to make the world a better place. They can do small things to help others, or larger scale things to help many people in the world. Look here for more information: http://socyberty.com/people/what-makes-a-hero/
Bravery is usually what makes a person a hero. This person will have overcome huge obstacles in their lives and made someone else's life better in the process. Heroes can be men, women, children, even animals!