This rare kanji has no clear standalone meaning. Treat its meaning as uncertain.
The exact historical development of 宯 is uncertain. It visually combines 宀 (roof) and 孝 (filial piety), but the original meaning and component relationship are unclear.
With no clear meaning, picture a roof 宀 over filial piety 孝 as a house where respect is taught, but remember the meaning is uncertain.
For コウ, imagine a child under the roof practicing filial piety by saying 'こう' (like this) as they learn proper behavior: こう -> コウ.