"The man walks in the library."
Translation:남자가 도서관에서 걷습니다.
-에서 is used to say where someone/something is from and it is used when there is action going on at a location. For example: "집에 있어요" would mean "I am at home". However, "집에서 먹어요." would mean "I eat at home". There is a verb involved at the location. In this case it is -에서 instead of -에 due to the verb.
"How can we know if it's 'from' or 'in'?" - I have this exact same question.
So "The man walks in the library" and "The man walks from the library" are both "남자가 도서관에서 걷습니다." ?
Edit: Came back to answer my own question. I could be wrong but I think "The man walks from the library" is "남자가 도서관에서 걸어갑니다." Using ~가다 to form a compound verb, it indicates motion to (~에) or from (~에서). Without ~가다, 걷다 is simply an action. I hope I got it right.
에 vs 에서:
The place marker ~에 is used to indicate a static place There are four verbs that are usually used with this marker, they are: 있다, 없다, 가다 and 오다. (exist, not exist, go and come)
저는 도서관에 가요. I go to the library.
물을 집에 있어요. There is water at my house.
The place marker ~에서 is used to indicate the place where an action takes place, like eating or laughing etc.
저는 도서관에서 웃어요. I laugh at the library.
저는 집에서 물을 마셔요. I drink water at my house.
I might be wrong, so please if I am someone correct me, but 하 is always part of certain verbs, not part of the ending for all verbs, so you just have to add ㅂ니다, since 하 ends with a vowel. You would add 습니다 is the verb ends with a consonant.
For example, 수영하다 (to swim) would become 수영합니다.
Using neun (는), as in nam-ja-neun (남자는), you emphasise that this particular man is doing something. For ga (가), as in nam-ja-ga (남자가), you don't put too much emphasis on the man that is doing something. Overall, both ga (가) and neun (는) serve similar purposes. It depends on whether you choose to emphasise on the man or not.