A girl finally gets a rare moment alone, and the poem watches her from a distance as she sits on cold grass, curls into herself, and rocks. From behind, she might look calm, even like she is meditating. But the speaker shows us what nobody else sees: her face frozen in a scream that never makes a sound. The poem suggests she has been holding in fear or pain for a long time, and that solitude is the only place it can surface at all.
The mood is tense, lonely, and hushed. Even the leaves stay still, as if the whole scene is afraid to set something off. The cold grass and the loud music she doesn't understand make her feel numb and cut off. The single tear is the only thing that escapes, and the last line, where it freezes like she did long ago, suggests this pain is old and that she learned to shut down in order to survive.