Rhonda is from the Welsh Rhondda — a valley and river in South Wales, from rhon ("pike, lance, spear") + the intensifier -dda ("good") — or alternatively "noisy one." A top-50 US baby name from 1961 to 1969, peaking at #44 in 1963. and Summer Days albums. Corral (1957). Rhonda Rousey is Ronda Rousey (different spelling). Rhonda Stark — Married... with Children.
Rhonda 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 Rhonda reduce to 6, The Nurturer. This is a traditional interpretive system, not a factual claim about the name.