As for 맛있게 드세요, Seulgi explained it in detail. 먹다 (the infinite form) = to eat 먹어요 (is the present conjugation of 먹다) 드세요 (a polite way of saying 먹어요) You cannot say "저는 잘 드세요", which means that we don't use "드세요" when the subject is "I" in sentences. "맛있게 드세요" is like, "Bon appétit" So when a host says it, how are you going to response it? Then, you can say like this: "잘 먹겠습니다(or 잘 먹을게요 = I will eat it well)" , "맛있게 먹겠습니다(or 맛있게 먹을게요 = I will eat it deliciously)", "감사합니다(or 감사해요 = thank you)" the host : "맛있게 드세요" Guest A : "잘 먹겠습니다." Guest B : "맛있게 먹겠습니다." Guest C : "감사합니다."

맛있게 deliciously 드세요 please eat So basically it means please eat deliciously And the real meaning is Help yourself or please enjoy the meal! :)