Lurdes is from the Portuguese Lurdes — Portuguese-Brazilian rendition of Lourdes — referring to the Catholic devotion to Our Lady of Lourdes (Notre-Dame de Lourdes). Lurdes is one of the Portuguese + Brazilian Marian-devotion feminine names — central to traditional Portuguese + Brazilian + Galician Catholic heritage. The Lourdes Sanctuary is one of the Marian pilgrimage sites worldwide (~6 million pilgrims annually).
Lurdes 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 Lurdes reduce to 7, The Seeker. This is a traditional interpretive system, not a factual claim about the name.