Symbolism, Imagery, Allegory
Everyone has a favorite outfit, and the going look for Afghan men and women is the shalwar kameez. The shalwar is flouncy pajama-like pants and the kameez is a long tunic, and these outfits tell us a lot about their owners and the different roles they play in this book. But let's look at a few characters and their shalwar kameezes to better understand what we're talking about.
Mother decides to send Parvana's shalwar kameez with her to market, in order to Parvana to sell it. Parvana's not having it—she yells, "We can't sell that!" (2.29)—but Mother wonders why they shouldn't. She tells Parvana, "there's no longer any use for it" (2.30), and when she does we understand that Parvana isn't just dressing up as Kaseem for a couple of days—nope, she'll be going undercover as a boy to help support her family for as long as necessary. And because of this, her old clothes—her shalwar kameez—is no longer necessary.
Nooria, on the other hand, needs to dress for success. As the oldest daughter, she is ripe for the picking and will need to look nice when prospective husbands coming knocking, so her clothes stay safely at home and are decidedly not for sale. Since the family sells anything that isn't absolutely necessary, we can see that Nooria's marriage is a top priority for the entire family.
Meanwhile, Hossain's shalwar kameez serves as a painful remember of his loss. It's pale green, like tree buds in springtime, and thereby symbolizes both the energy of his youth and that he was killed before his time. Hossain's shalwar kameez stays in the closet—which we can see as symbolizing his death (it's like it's buried in there)—until the time comes for Parvana to put it on and become Kaseem.
When Parvana dons Hossain's shalwar kameez, it's too big—but she enjoys the shirt pocket because "her girl clothes didn't have any" (6.46). This difference between her girl clothes and the boy clothes she now wears is exemplified through the pocket. And since pockets are nothing if not useful, the presence of a pocket reminds us that Parvana is stepping into a very useful role on behalf of her family. Just like pockets carry stuff you put in them, Parvana is carrying her family's well-being.
Father's shalwar kameez, though, is probably the most symbolic. After his nap, he combs his beard and dresses in his "good white" outfit, and Parvana notices that he looks "very handsome" (2.48). Then the family gathers round him and he tells stories from history, and gives them words of wisdom. In his fancy outfit, he seems like a god or something—and when he wears it, he leads his family in a sort of god-like fashion, educating them though the Taliban forbids it and investing in their futures though they live in a sea of poverty and violence.
Father's shalwar kameez doesn't stay white for very long though, and during his kidnapping, he is hit in the face, and blood from his nose stains the garment. Father is hurt and his shalwar is stained—and this is the last we see of him as he is dragged off to prison. When Father eventually returns, he's still wearing the shalwar kameez, although it is "gray and tattered" (15.1)—just like he is. But though the garment has seen much better days, it's still standing—again, just like Father.