The letter Nun [נ] is the symbol for soul, the heavenly spark housed in the earthly container of the body. The soul is the self, taking in intellect, will and heart. The shape of the letter leads many to associate it with humility: nun is “the servant bent over”. Hebrew numerology students love to add up the sum of the letters in words to figure out what they signify. The letters in the name “David” add to fourteen, so they associate the great King of Israel with this letter, as well as Messiah, his descendant; the perfect servant and the epitome of humility. (Nun is the fourteenth letter of the Hebrew alphabet.)
Nun is also the word for “fish” in Aramaic, and Hebrew scholars refer to it as the fish that swims in the water of the Torah. Some of this is a bit too mystical for me, but I find these things of interest.