The statue is not very special. Just a torso. In fact, it is rather damaged. It probably represents Penelope, the wife of Odysseus. It’s in wet drapery style, so it dates to the second or third decade of the fifth century. Because it’s made of Pentelian marble, we know it’s from Athens. Nothing special.
What makes it unique, is the place where it was found: the Treasury of the royal palaces of Persepolis. Which explains why it’s now in the National Archaeological Museum of Iran in Tehran. The question how an Athenian statue came to Persepolis is easily answered: it must have been stolen in Athens when the Achaemenid king Xerxes looted the city in September 480. This damaged torso is a silent witness to an almost legendary war, and that’s what makes it unique.