Today’s feast day is the Holy Name of Jesus. Before the calendar reforms of the late 1960s, this celebration was held on January 2nd. It was removed outright from the calendar until 2002, where it was added to January 3rd.
In the General Instruction of the Roman Missal, we’re instructed that during the Mass, we’re to make a bow of the head when the three Divine Persons are named together, the name of Jesus, Mary, and any mention of the Saint whose feast day is being celebrated in the Mass.
A noble devotion is to not limit this to Mass, but generally bow your head at the mention of Jesus always. For me, it’s a small acknowledgment of the Biblical exhortation that at the name of Jesus every knee should bend and a similar devotion to one of making the sign of the cross when passing by a church.