Heroic means having the qualities of a hero, such as bravery. Maybe on your daily walk, you see a house on fire, and you run into the flames repeatedly to save the family and their pets, including the fish! That’s heroic.
Literature offers many examples of heroic characters, who by their strength or their wiles or both overcame almost impossible obstacles. In Greek mythology, Hercules was given seven seemingly impossible tasks that he completed with heroic daring, Achilles was a warrior whose accomplishments in battle were heroic, and Odysseus showed his heroic qualities as he conquered monsters and men in his journey home.