ke + luar
1) to go out, to get out, to exit
2) to emerge, to show up
Kapal selam itu keluar dari samudera.
The submarine emerged from the ocean.
3) to be announced
4) to retire
5) to take (s.th.) out
6) to remove
7) to discharge (an employee)
8) to issue (a ticket etc.)
9) to produce
(to emerge, to come up) muncul, sembul, tongol
I believe that in many languages, English included, certain verbs are largely paired with certain prepositions. Here, "keluar dari" where we might say "go out of." In English, for example, you have to "ask for an apple" when you want to request an apple==>ask [direct object; e.g., "someone"] for [sort of indirect object, here, object of a preposition; e.g., "something"]. Compare that to "request 'something' from 'someone'."
My Indonesian language teacher explained to me that "keluar" has a slightly different meaning from, say, "berangkat" or other Indonesian verbs that we would look at largely as synonyms. "Keluar' means simply to go out [from somewhere]. "Pergi," for example, is even more simple in the sense of just going with no particular destination implied. "Berangkat" means to leave with a destination very much implied, hence you would see this at the airport. I would welcome native Indonesian speakers correcting my understanding.