Brown from the sun's mid-afternoon caress, And where not brown, white as a bridal dress, And where not white, pink as an opened plum.
And where not pink, darkly mysterious, And when observed, openly furious, And then obscured, while the red blushes come.
Think of someone's skin being described patch by patch, as if the speaker were moving slowly across it. First comes the brown left by afternoon sun, then the pale, bridal white where the sun never reached, then a soft plum-pink. The mood starts out warm and admiring, almost lazy, and the description feels loving and a little sensual.
Then the second stanza turns. The next shade is "darkly mysterious," and when the speaker looks closer, it becomes "openly furious." Something that seemed calm and pretty now has a temper. Judging by the language, the poem seems to be about a person, though it never says so outright, and the colors work like moods flickering across a face or body. The last line brings in red blushing, as though the person feels watched and reacts to it.
The overall effect is playful but charged: beauty on one side, unease on the other, all packed into six lines and a tight rhyme scheme.