MV> "Juf" is short for "juffrouw" which means "miss". So a female teacher.
Sounds like it was derived from the German "Jungfrau", which originally meant "virgin" but meanwhile is applied to all underage females, although the term is only rarely used nowadays.
The German term for a female teacher is "Lehrerin" (the "in") at the end indicates "female". A "Lehrer" is a male teacher. Have to make some distinction to avoid calling a woman "Mr." or a man "Ms.".
Incidentally, the "Ms." would correspond to the German "Frau". The term "Fraeulein" (Miss), which was commonly used for underage or unmarried women, is meanwhile no longer in common use, except maybe in restaurants with waitresses where you call "Fraeulein!" to summon one. But I can't say for sure, since I haven't been in a restaurant for quite some time.
