The day of the candles the reason for this tradition is to celebrate the Immaculate Conception of the Blessed Virgin Mary, The Immaculate Conception takes importance in the field of Christmas because the Blessed Virgin was prepared from the moment of her conception to be the mother of Jesus, being part of the plan of salvation, because for the son of God to reach the world, a woman who lacked original sin was needed. the ideal is to celebrate the eve by lighting candles and praying a family rosary
Beautifully put!