The title points to Marie Antoinette, though the poem never says so outright, and the speaker never describes her directly. Instead we get small, odd glimpses. She has lost her own garden and been left with a "red bed of velvet," a rich but enclosed place, more like a display than a home. Calling the queen "pretty as a horse" is an unsettling comparison: it makes her look like a well-groomed animal, admired for her appearance and kept in a stall. She is also "full of time," which suggests she has nothing to do but wait.
The last couplet is the strangest. A blade seems to threaten the bread, which is "idle," and the sight of it is "sad." Judging by the title, the blade may hint at the guillotine, but the poem leaves that unspoken. The mood is quiet, hushed and faintly ominous. The speaker seems to watch with a mix of pity and detachment, noticing beauty and doom in the same image.