Marta is the Spanish, Portuguese, Italian, Polish, and Scandinavian form of Martha — from the Aramaic martā ("lady, mistress of the house"). Globally known by mononym "Marta".
Marta 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 Marta reduce to 8, The Visionary. This is a traditional interpretive system, not a factual claim about the name.