This small panel depicts the Martyrdom of St. Lucy. After refusing to marry a wealthy suitor, Lucy was subject to repeated trials and tortures, each of which she miraculously survived. She was finally killed by a sword, which we see here. The train of oxen refer to one of her many torments. The priest to her right offers her the wafer of communion and forgiveness before her death.
St. Lucy is usually portrayed holding a tray with her eyes on it, referencing another torment. Because of this association with sight and light she is celebrated in Scandinavia on December 13th on the eve of the winter solstice, where she is honored as the harbinger of daylight, spring and rebirth in the time of deepest darkness.