Prudence is from the Latin prudentia ("foresight, wisdom") — one of the four classical cardinal virtues alongside Justice, Fortitude, and Temperance. Saint Prudence of Como (5th c.) was an early Italian martyr.
Prudence does not currently appear in the US Social Security Administration's top 1,000 girls' names, so we don't publish a US rank or birth count for it. That says nothing about the name's standing elsewhere in the world — only that it sits outside the ranked US data we rely on.
In Pythagorean numerology the letters of Prudence reduce to 5, The Seeker. This is a traditional interpretive system, not a factual claim about the name.