Meaning: from Greek ion meaning "violet".
In Greek mythology Iole is the daughter of Eurytus, king of Oechalia. He was a very skillful archer, having even taught Heracles, which is ironic later on when Eurytus offers his daughter as a prize to whoever can beat him and his sons in an archery contest. Heracles wins the contest but Eurytus refuses to give his daughter to him since he had killed his previous wife, Megara, as well as their children and was afriad the same thing would happen to Iole.
Eventually, Heracles marries Deianira, daughter of the king of Calydon, but he never forgot about Iole and now that he had an army at his disposal he invaded Eurytus's city, killing him and his sosns and capturing Iole as his concubine. This ultimately leads to his death because Deianira, jealous of Iole's youth and beauty and afraid that Heracles would leave her forever, makes a potion given to her by the centaur Nessus (who'd attempted to kidnap and rape Deianira before Heracles rescued her and killed him) from some of his blood, telling her that it would keep him forever faithful to her. However, it turns out to be a lie for when she sprinkles it on his shirt and he puts it on, it burns Heracles terribly, driving him mad and causing him to throw himself on a funeral pyre.
It's pronounced ee-O-lee or Ei-o-lee.