The most common Korean word for “happy” is 행복하다 (haengbokada). There is one more word with a similar meaning — compare them below. 「happy」는 한국어로 행복하다.
happy; content; joyful
TOPIK 1 · adjective
happy; glad
TOPIK 1 · adjective
Words and levels: TOPIK I essentials (National Institute of Korean Language standard curriculum, KOGL Type 1) · examples: Cheesepotato