This is the 1576th most frequent Korean word.
다니는
"Attending" or "going (regularly)."
다니는 is used here as a present participle to describe the student who is regularly attending school.
학교에 매일 다니는 학생입니다.
The student who goes to school every day.
다니는 is employed to describe the daughter who frequently visits her parents, indicating habitual movement.
부모님께 자주 다니는 딸이에요.
She is a daughter who visits her parents frequently.
다니는 중 means 'in the process of attending,' indicating an ongoing habit of visiting the gym.