This rare kanji has no clear standalone meaning. Treat its meaning as uncertain.
俲 combines 亻 (person) with 効, which likely contributes both sound and meaning related to imitation or learning. The exact historical development is uncertain.
A person 亻 beside 効 (effectiveness) suggests learning by imitating effective actions, but the meaning is unclear.
For コウ, imagine a person learning to imitate a koh (invented sound) from an effective teacher: koh -> コウ.