Jadwiga is the Polish form of Hedwig — from the Germanic hadu (battle) and wig (strife). Queen Jadwiga of Poland (1373-1399) reigned as King of Poland (the female monarchical title) and was canonized as a saint in 1997.
Jadwiga is widely used in Poland.
Jadwiga 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 Jadwiga reduce to 1, The Leader. This is a traditional interpretive system, not a factual claim about the name.