Burginda is from the Old English burh (fortress) and a feminine suffix. Burginda (8th c.) was the Anglo-Saxon nun who inscribed her name in the Boulogne Gospel — one of the few named female scribes of the early Anglo-Saxon period. Her colophon survives.
Among the earliest named English female scribes.
Burginda 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 Burginda reduce to 4, The Builder. This is a traditional interpretive system, not a factual claim about the name.