The English accents of the three people in the stall at the bazaar in James Joyce's "Araby" reveal to the narrator that they are from England rather than from exotic Arabia. 

"Araby" is a form of Arabia, and both the narrator and Mangan's sister fall for the gimmick.  They are both victims of romantic illusions, and they think that the bazaar is actually a travelling exhibit/bazaar from Arabia--a far away and exotic destination.  The name is a gimmick, though.  The bazaar, apparently, originates in England and not Arabia.  It's nothing special:  there's no great crowd attending it, it's virtually closed by the time the boy arrives, and nothing too impressive is on display and for sale. 

And, as you noticed, the narrator "remarked [noticed] their English accents."  He also overhears their conversation:

"O, I never said such a thing!"
"O, but you did!"
"O, but I didn't!"
"Didn't she say that?"
"Yes, I heard her."
"O, there's a...fib!"

Not only are the three from England--a country the Irish hate anyway--rather than from Arabia, but their conversation is nothing more than silly, trivial flirting.  There's nothing special going on at this bazaar.

This, of course, leads directly to the narrator's epiphany, his realization that he has been silly and trivial himself;  that he has been blind--like the street he lives on. 

Gazing up into the darkness I saw myself as a creature driven and derided by vanity: and my eyes burned with anguish and anger.