Answer:
...
Step-by-step explanation:
Because it is used to show a longer pause or an omission. In dialogue it shows the character is pausing in between speech or deliberately not saying something aloud but rather implying it. In narration it has the same function; it just would not be part of dialogue punctuation.
Ex. "Maybe it was an accident . . . Ginny seems to really not know what happened," said her father.