The most common Korean word for “turn on” is 켜다 (kyeoda). There is one more word with a similar meaning — compare them below. 「turn on」는 한국어로 켜다.
to turn on; to light
TOPIK 1 · verb
turn on (device); twist
TOPIK 2 · verb
Words and levels: TOPIK I essentials (National Institute of Korean Language standard curriculum, KOGL Type 1) · examples: Cheesepotato