Ha and her family have managed to flee from the turmoil in their native Vietnam. They're traveling aboard a Navy ship that will take them to safety.
As there are thousands of other desperate refugees aboard, food supplies have to be rationed out. Water is also in short supply, and the passengers have been told that they must only sip water when they must so that their bodies will stop needing it. But as Ha ruefully reflects, her body won't listen. Other girls may be like bamboo, "bending whichever way they are told," but not Ha.
Ha's so hungry that she starts imagining that she can smell food when it's not there. She claims that she can smell "sardines, dried durian, salted eggs, [and] toasted sesame." But of course, no one is offering any such food; it is all in the mind, a figment of a hungry child's overactive imagination.
Ha's imagination is much in evidence a little later on when she eats her rice ration. As soon as she bites into her little clump of freshly cooked rice, all "plump and nutty," she imagines the taste of ripe papaya, even though the taste of one has absolutely nothing whatsoever to do with the other.