Language/Korean: -는 곳

We sometimes find 나가는 곳 close to exit door. What's it meaning?

Let me copying an article from letslearnkorean.com

Pattern:
(noun +) verb stem + -는 곳

These signs identify places where you do something: buy tickets, change trains, etc.

곳 is a dependent noun (의존 명사) meaning “place.” (A dependent noun is a noun that can never occur on its own, but must be qualified by a determiner, number, verb, or adjective immediately preceding it.)

-는 is a verb ending that serves two simultaneous purposes:
(1) It transforms a verb so that it can modify a noun or dependent noun that follows it; and
(2) It describes an action that is occurring in the present (or ongoing).

For example, 읽는 학생 means “the student that is reading,” and 흐르는 물 means “flowing water.”

So -는 곳 together means “the place where something is happening.” Here are some examples:
※ At many public attractions, you buy tickets (표를 사다) at a 표 사는 곳.
※ When waiting to board a subway car (차량을 타다), you may be standing at a 차 타는 곳.
※ When changing subway trains (지하철을 갈아타다), you follow the signs marked 갈아타는 곳.
※ When exiting a subway station (역으로부터 나가다), you go out through a 나가는 곳.
※ When you enter a 고속 도로 (freeway), you receive your ticket (표를 받다) at a 표 받는 곳.
※ When you leave a freeway (at a 나가는 곳 like on the subway), you pay the toll (돈을 내다) at a 돈 내는 곳.
Some of these places have alternative names. 표 사는 곳 is also called 매표소 (賣票所), which literally means a place where tickets are sold. 차 트는 곳 is sometimes called 승차 위치 (乘車位置), which means exactly the same thing. The words 나가는 곳 are always accompanied by the Hanja 出口 (출구), which means “exit.”

Source : http://letslearnkorean.com/index.php/korean/comments/neun-got/