The title gives us the situation: a woman whose child has become the latest victim of something, probably violence, though the poem never says what. We don't see her face or hear her speak. Instead we get two small, sharp images of what the news does to her body and mind.
In the first, noon is "like a hard note / sealed up in her soul." Midday, usually the brightest, most ordinary hour, turns into a single sustained sound that she can't escape. The word "sealed" makes it feel permanent, as if the moment has been locked inside her. In the second, her "ear sore with the news" suggests she has heard the same words again and again, until the hearing itself hurts. "Beating in" works like a pulse or a knock that keeps coming.
The mood is stark and numb. The poem is short and quiet, and that restraint makes the grief feel all the heavier.