Jana is from the Czech / Slovak / German / Dutch Jana — Central European feminine of John — from the Hebrew Yochanan (Yahweh is gracious). Jana is one of the Czech + Slovak + Dutch + German + Slovenian + Croatian feminine names — consistently among the most-popular feminine names across Central Europe + the broader Slavic + Germanic linguistic spheres.
Jana 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 Jana reduce to 8, The Visionary. This is a traditional interpretive system, not a factual claim about the name.