Ravana was king of Lanka. He had ten heads. He took away Goddess Sita, wife of Lord Rama (an avatar of Lord Vishnu). Lord Rama attacked him. He and his army fought with Ravana, with the help of the monkey army of King Bali and his army. At last, Ravana was killed.
When Lord Rama returned to Ayodhya (his native place), Someone told that a woman who lived with other men should not stay with her husband. so Lord Rama sent Goddess Sita away to the forest. This tells us that Lord Rama didn't give respect to his wife who had made many sacrifices for him.