Bronwen combines the Welsh bron (breast) and gwen (white, fair) — meaning "fair breast." In medieval Welsh poetry, the Mabinogion's Branwen (a related name) is the heroine of a tragic tale.
Bronwen is widely used in Wales.
Bronwen 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 Bronwen reduce to 1, The Leader. This is a traditional interpretive system, not a factual claim about the name.