This painting is part of an altarpiece, the main panel of which depicts The Virgin and Child. This section shows Saint Philip; other parts of the altarpiece show Saints Peter, John the Evangelist and John the Baptist.
Philip became one of the Twelve Apostles after meeting Jesus through John the Baptist. He was the disciple who Jesus asked to gather food from the crowd before miraculously multiplying it. Philip is thought to have died a martyr's death by being stoned and crucified, and so is often pictured holding a cross.