Yn (Ꙟ ꙟ) is an archaic Cyrillic letter. It looks like the Cyrillic letter Psi (Ѱ ѱ) turned upside down.
It was used in the Romanian Cyrillic alphabet, where it represented the sounds, and at the beginning of words. In the modern Romanian alphabet it is replaced by ⟨în⟩, ⟨îm⟩, or ⟨î⟩.
Read more about Yn: Computing Codes