The most common Korean word for “exercise” is 운동 (undong). There is one more word with a similar meaning — compare them below. 「exercise」는 한국어로 운동.
exercise; sport
TOPIK 1 · noun
exercise; take exercise
TOPIK 1 · verb
Words and levels: TOPIK I essentials (National Institute of Korean Language standard curriculum, KOGL Type 1) · examples: Cheesepotato