"있는 것" 있는 is a present tense conjugation of 있다, which means "to be/stay somewhere".(To exist is its another meaning). It is similar to the present participle in English, like "staying", describing an ongoing action or state. 것 is an abstract noun here for an "act" or "fact", so 있는 것 means "the act of being/staying". For example: 1. 책을 읽고 있다 = (I) am reading a book. 2. 책을 읽고 있는 것 = to be reading a book. (noun phrase of #1) 있다 and 있는 have many other usages besides -고 있다. - 길 건너에 은행이 있다 = There is/exists a bank on the other side of the street. - 집앞에 한 남자가 서 있다 = A man is standing in front of the house. - 집앞에 서 있는 남자는 아빠 친구였다 = The man standing in front of the house was a friend of my father's. - 나 오후엔 집이 있을 거야 = I will be home in the afternoon. (your example) - 두 사람이 함께 있다 = The two are together. - (두 사람이) 함께 있는 것 = (The two) being together. (noun phrase) - 함께 있는 것만으로 = just for/by being together. (-만 = only, just; -으로 = for, by (reason or means)) - 함께 있는 것만으로 눈물이 나요 = I tear up just for/by being together (with you).