This is the 9208th most frequent Korean word.
건우는
"건우는" means "Geon-woo is" or "Geon-woo" (used as a topic, with the Korean topic marker "는").
In this sentence, '건우는' specifies the subject 'Geon-woo.' It marks him as the person being talked about and emphasizes the action he performs, which is studying.
건우는 학교에서 공부를 열심히 합니다.
Geon-woo studies hard at school.
Here, '건우는' again identifies Geon-woo as the subject of the sentence, and the statement expresses his preference for exercise.
건우는 운동을 좋아합니다.
Geon-woo likes to exercise.
In this third sentence, '건우는' situates Geon-woo at the focus of the action, describing an activity he engaged in during the day.