It depends on any accent mark.
Without any markings, I would pronounce it "NOLE," as in
Noel Coward and assume it was a boy's name.
If there are two dots over the "e," then I would pronounce it "no-ELL," as in "The First Noe"l" or the French word for
Christmas. I would consider this to be a girl's name, the same way
Summer,
Autumn,
Winter are.
BTW, I intensely dislike the
Noelle spelling.