Gazing up into the darkness I saw myself as a creature driven and derided by vanity; and my eyes burned with anguish and anger.
James Joyce is known for is his use of epiphanies: "a sudden spiritual manifestation, whether in the vulgarity of speech or of gesture or in a memorable phase of the mind itself" (Stone 371).
The last line of "Araby" can be seen as the boy's epiphany. Leading up to this moment, Mangan's sister has consumed his mind, and he thought buying something for her from Araby would solve everything. Now that he finally made it to the bazaar, he is utterly disappointed.
There are many interpretations about what the boy's epiphany actually is. Some scholars posit that the he relates to the men flirting with the sales woman: "The boy looks steadily at this vulgar avatar of his longings; and then his other vision—his vision of a comely waiting presence, of a heavenly dolorous lady—dissolves and finally evaporates. The boy, at last, glimpses reality unadorned; he no longer deceives himself with his usual romanticizing" (Stone 371). He is ultimately just like those two men, and Mangan's sister is just another girl.
Another possible interpretation is that the boy's realization is a greater metaphor for the deterioration of Ireland's identity. He sees the French "Café Chantant". Moreover, while eavesdropping on the lady and the two men, the boy "remarked their English accents". Perhaps Ireland is not so Irish anymore.
Yet another meaning could be that the boy is no longer a boy; he has transitioned out of the magical and imaginative world of being a child. The story begins with the boy telling us how he and his friends, "played till our bodies glowed". He then stops playing with his friends because he is infatuated with Mangan's sister: "From the front window I saw my companions playing below in the street". After he hears about Araby the boy has "hardly any patience with the serious work of life which, now that it stood between me and my desire, seemed to me child’s play, ugly monotonous child’s play". His whole outlook on life has rapidly changed. In an essay titled "Closing Time: 'ten minutes to ten' and the End of Childhood in Joyce's Araby'", Steven Doloff notes that the boy arrives at the bazaar at "ten minutes to ten": "While clock hands regularly meet twenty-four times during the course of a day, their particular occurrence at 9:50 P.M. at the end of 'Araby' may have a special contextual significance. Their juncture immediately precedes the boy's anguished self-revelation and what appears to be the near-simultaneous closing of the bazaar at ten o'clock. If we choose to see the longer minute hand of the clock as representing adulthood and the shorter one childhood, then 'ten minutes to ten' would symbolically portend the moment that adulthood overtakes the boy's childhood, eclipses it, and begins to leave it behind—a simple visual icon for a widely acknowledged theme in the story".
These are just a few of many interpretations of the ending. Ezra Pound wrote that Joyce's "most engaging merit, is that he carefully avoids telling you a lot that you don't want to know".