Forked Tongue

The setting is the late 1940s or early 1950, when a group of characters, survivors of the Nazi atrocities, have arrived in America.  

Although the narrative has not told us, without giving the matter much thought, we assume they were speaking German or Yiddish or possibly Russian, maybe even Polish.  We don't need to be accorded the usual narrative device "He (or she) said in [fill in the language].

Now, they have arrived in America.  One of them begins to speak in another language.  The other holds up a hand.  "We should speak English from now on."  Whether they lapse into the occasional Yiddish or Polish or German is another matter.  That one line of dialogue reminds us to the point where we no longer have to think about it that they are speaking English.

Perhaps, as the story progresses, they are in a social or commerce situation, attempting to purchase something at a store or order something in a restaurant.  An American clerk says, "Sorry.  It's your accent.  What were you asking for?"

While we're on the subject of accents and dialect, the writer can step in with a description such as, "She spoke in a heavily accented whisper, somewhere between French and those secret-sounding Slavic tongues."  

This brings in description and attitude, although these come from the writer, which means the writer has felt the need to get in there with tells or descriptions that are better coming from the characters,  "Eat ease airly jet."

There is dialogue in which terminal g's are omitted.  "Ya comin'?"  or regional dialogue in which car keys turn out to be a type of trousers rather than the means to enter and start an automobile.

Such things are the handholds the author gives the reader without having to stop the story for explanations, which, when taken to extremes, are reminders to the reader that this material is set in a false reality, populated with inventions of actual people.  However we may give street names, Lexington Avenue, Hester Street, Broadway, however the characters venture into a Horn and Hardart Automat, their pockets jingling with coins, this is a simulacrum of Manhattan, not the real one.  However much the characters are based on one or more actual persons, these are inventions, not real people.

In an ironic vision, we might say of a real person named John, "John was impatient."  In a story, we say of John that "He drummed his fingers on the tabletop. "  Or we might say, "John consulted his watch."  

We may even bring another invention of a character into the scene to approach John. "Let's face it," this invented character will tell John, "you've been stood up.  Two hours you're sitting here, drinking coffee, smoking god knows how many cigarettes, she's still not here.  What is it about stood up you don't unnerstan'?"  Thus has the writer shown or demonstrated as opposed to told.

These elements all come under the heading of conveying to the reader relevant information the writer believes will contribute to the reader's deeper appreciation of the story.  In all likelihood, there will not be a uniform standard of what information to show.  Some writers and their readers are fine with being told "It was raining."  You go out of your way to avoid such use, even reaching the point where you'd be happier saying in dialogue 
"Depends." or even "All depends." instead of "It all depends."

You admire writers who are able to find ways to convey the desired information, often as much by severe indirection or subtext as by artful showing.  There are times when, if you can't find a way to get the desired information into a story, the information does not belong.