This character is an ñ. This particular ñ is a sign above a restaurant in Inwood, a neighborhood at the very northern end of Manhattan. Phonetically, the sound that it produces is represented as /ɲ/. The grapheme (symbol, character) entered Spanish in the thirteenth century, as part of the orthographic reforms of Alfonso X, known as the Wise. Manuscript evidence suggests that it represented a transformation of an earlier representation of that sound as nn, next to each other, to nn, one stacked on top of the other — a space-saving measure followed by the shrinkage of the top n into a ~. (Still unpacking post-move, and all my history-of-the-language teaching materials are still in a box somewhere, otherwise I’d find a couple of good manuscript images where this happens…)