It's a subject marker. It means "man" is the subject of the sentence. Since 남자 ends in a vowel, ㅏ, you add 가. 남자가. For a word like 연필 (pencil), since it ends in a consonant, ㄹ, you would add 이. 연필이.

I believe so

Yes

you do

♪Sooo faaaaaaaar awaaaaaayyy~ ♫

Yeah same. My secret husband Jeon Jungkook (he doesn't knows it yet) is there but he's so faaaar away~ ;(

Same with RM hahaha

I think it's because of the 에 before 한국 that signifies he is "in" Korea.

Also using 사람 is also a good indicator of nationality versus location.

I think if they refer to a nationality they use 사람. Like 미국 살림 is American.

so true, it has the same meaning and i would rather use is then their sentence, because there is no "the" in korean otherwise it would be something like "i namjaga" or "keu namjaga"

입니다 = am/is/are. 있습니다 = there is/are, have/s

I think 입니다 means ^have^and 있습니다 means ^to be ^

yes. to have or to be in a location. on this case means to be somewhere, this why they used the location marker 에

I believe it's 난자가 한국 사람입니다, which translates literally to: man Korea person-is

No. The particle 에 is used as a location marker. 그 남자는 한국 사람입니다 would be ,,The man is Korean.” Here you also use another verb - to be 이다.

Location particle