Leda (Λήδα) is from the Lycian lada (woman, wife). Spartan queen, mother of Helen of Troy and the Dioscuri (Castor and Pollux) — Zeus came to her in the form of a swan and she laid two eggs, from which the four children were born. Yeats's Leda and the Swan (1924) is among the most-anthologized poems of the 20th century.
Featured in Euripides's Helen and Apollodorus's Library.
Leda 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 Leda reduce to 4, The Builder. This is a traditional interpretive system, not a factual claim about the name.