Typo of "you", mostly used on purpose by far right groups as a dogwhistle. Originated from 4chan memes.
A dogwhistle used by the right wing community. "yuo" is just a mispelling of "you" it doesn't have any hidden meaning, it's just a misspelling used by right wingers (or sometimes not only right wingers, just people interested in politics) to recognize each other.
person 1: Hey, how are yuo doing?
person 2: Heyyy.... waittt.... is that a dogwhistle!?!?
person 1: Well.. yes it is