Barbara (from Nicomedia) was the daughter of a pagan noble who worshipped false gods. Because of her striking beauty, her father enclosed her in a tower to hide her from the snares of men. Barbara vowed virginity, and during an absence of her father had a third window added to her quarters in honor of the Blessed Trinity; at the same time, she also adorned her bath with the sign of the holy Cross. Upon his return her father was so angered over these changes that a miracle was needed to save her life. She was presented before the magistrate, subjected to much torturing, and finally her own father wielded the sword that severed her head. Immediately God's vengeance struck him dead. The holy virgin is highly honored both in the East and the West as patroness of artillery men and of miners. She is especially invoked for preservation from sudden death. She is one of the "Fourteen Holy Helpers."

In the past, the following prayer to St. Barbara was often recited:

Saint Barbara, thou noble bride,
To thee my body I confide
As well in life as at life's end.
Come, aid me when I breathe my last,
That I may, ere here all is past,
Receive the Blessed Sacrament!

In certain parts of Europe, the so-called "Barbara branch" is brought into homes today. It consists of a small cherry twig that is set in water and should blossom on Christmas eve. The custom is deeply Biblical and liturgical. "The bud from the root of Jesse and the flower from its root" is Jesus Christ, whom we expectantly await during Advent and who will blossom forth as a flower at Christmas.

http://www.catholicculture.org/culture/liturgicalyear/calendar/day.cfm?date=2013-12-04