In this image, the donor is seen worshipping, almost as if in a direct conversation. For the donor, this both serves as a reminder that Christ answers prayers and displays her piety for everyone to see.
Most likely cut down from a larger painting, probably on the other side would have been the Virgin Mary and Christ child. People in Northern Europe venerated Mary above all other saints, so her image is very common.
As the portrait has a plain dark background, of the type traditionally favoured for Burgundian court portraiture, a conventional reconstruction might also feature the Virgin and Child with a uniform dark background.