The short answer is "salvation!".
That is Mary Magdalen, one of my favourite saints. What makes her different from a lot of other saints is that she was believed to have been a sinner.
That is more complicated than it seems. First because all the saints believed themselves to have been sinners. If there is one thing about them that distinguishes them from you and me it is that that they were far more willing to condemn themselves as sinners than we are. They condemned themselves as sinners for things most of us would let go by. But the objectively told stories of their lives makes them sound like like paragons of virtue or, more than occasionally, rather boring.
Mary Magdalen, on the other hand, was widely believed to have really, really sinned and, even better, to have sinned in a sexual way. The Bible, however, gives no clear evidence of this. To make the sexual sinner story work calls for a lot of analogy and tradition.
Or you could just look at her face above. Whoever that look was intended for felt it in his hip pocket. At first glance you might think the look is intended for you but she doesn't quite make eye contact with you. Someone else is getting that privilege.
All of which is all the more shocking when you realize the scene this picture is meant to represent. That is jar of nard she is carrying and with which she will anoint Jesus (either upon the head or the feet, depending on which Gospel you read). In the Gospel of John, Judas complains that this nard could have been sold for an amount about equal to about years wages.
Now, as I say, you have to believe that Mary Magdalen and the woman who anoints Jesus with the nard are one in order to get the narrative implied here and the Bible gives no evidence for this. If you do, though, the story gets quite rich. It isn't just that the nard is worth so much that makes it fascinating but that this woman has some. How did she come by it? Was it a gift to her or did she (wink, wink) earn it?
If she did earn it, it's rather late in the story as all this happens just a few days before Jesus is crucified suggesting that, although the Magdalen may be a repentant sinner, she wasn't exactly a reformed sinner.
Everything we think we know about the past is wrong
Carlo Crivelli, the painter, is, in theory, an early Renaissance painter. His style and technique, however, were a throwback in his era.
That he would have identified with Mary Magdalen is clear from his first documented appearance in history when he was imprisoned for having abducted and committed adultery with the wife of a sailor in 1457. The "abducted" in his charge was almost certainly there to save face for the woman and her husband. Oh yeah, he painted the above picture a little more than a decade after his arrest.
As I've said before, we tend to take the middle ages and the early Renaissance as being as they wished themselves to be. There was far less unity of thought or morals during these eras than we imagine. They were also far wiser about sex than we like to pretend: Dante had a wife and mistresses in addition to Beatrice whom he is famous for not having. We tend to focus on the latter story because he wrote more about her.
The point being, those eras could give a more honest account of a repentant sinner than we can.