主

lord, chief, master, main thing, principal

Kun

ぬし · おも · あるじnushi · omo · aruji

On

シュ · ス · シュウshu · su · shuu

Kun is the Japanese reading, used when the kanji stands alone with kana after it. On comes from Chinese and is mostly used in compound words.

Radical

丶drop

Parts

丶drop王jadeform of 玉