What does to be as faithful as Penelope mean?

Penelope is a character from The Odyssey, a Greek Epic written about a man named Odysseus that is trying to find his way home from the Trojan War. Odysseus' wife is Penelope, and while Odysseus is gone, she experiences pressure from 108 suitors trying to remarry her. However, she stays faithful Odysseus. He finally returns 20 years later to beat the suitors and take back his palace.