Marketa is from the Czech Markéta — Czech rendition of Margaret. Marketa is one of the Czech feminine names — central to traditional Czech Catholic + post-Communist secular heritage.
Marketa 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 Marketa reduce to 6, The Nurturer. This is a traditional interpretive system, not a factual claim about the name.