용건 means a reason or purpose a person has to visit or call someone, a business or an office, etc. So it is business in the sense of "a thing to do" or "an errand to run" rather than an enterprise(사업) or a corporation. Your dictionary seems to use "message" to express this idea, but I think it's misleading. The only connection is when people take a message on the phone, saying 용건을 말해 주세요 (Give me the message to pass on to that person), meaning "What do I tell him or her the purpose of your call was?". Imagine a situation: someone shows up at a help desk in an office. Visitor: 안녕하세요. Help Desk Person: 네, 용건이 뭐예요? (What's the purpose of your visit?) = 무슨 일로 오셨어요? (What are you here for?) But 용건이 뭐예요? is too direct and rude sounding, so it is seldom used nowadays. Most businesses and government offices use much nicer sounding phrases than 용건. 용모 is unrelated to 용건 (용 here is a different hanja pronouncing the same). It means "a person's looks", like 모습. Perhaps you meant 용무. 용무 is a synonym of 용건, with a slightly broader sense of "a thing to do". 사업 is "business" in the sense of "enterprise" or "running a corporation", which has no connection to 용건. 음력설(음력 = lunar calendar, 설 = 설날) means new year's day in lunar calendar. 설날 just means new year's day, which is based on the solar calendar(양력) nowadays. 들어오다 is "come in" and 들어가다 "go in". They depend on where the speaker is at in relation to the action. Both are common native Korean words, like 오다, 가다, 나오다 (come out), 나가다(go out), and so on. 입장하다 is a hanja-base word meaning "enter a place (room, hall, stage, etc)". So it is more formal and not used in daily life as much as 들어오다 and the others.