"So soft, so calm yet eloquent,
..."See in text(She Walks in Beauty)
The adjective “eloquent” describes a person or speech that is persuasive, fluent, or forcefully expressive. Byron concludes the poem by implying that the woman’s physical appearance expresses her inner morality and purity—for her soft cheeks and winning smile ultimately “tell of days in goodness spent.”
"Where thoughts serenely sweet express
..."See in text(She Walks in Beauty)
The adjective “serene” means peaceful and untroubled. Byron believes that this woman only thinks peaceful, calm thoughts because her outward appearance is so beautiful. Further, he suggests that this woman’s beauty and untroubled thoughts reflect inner purity.
The adjective “gaudy” means tastelessly showy or extravagant. Byron suggests that the merging of darkness and light in the woman’s appearance is better than the showy brightness of daytime because it is a more “tender light.”
In this context, the noun “aspect” refers to the woman’s appearance, particularly her face. Byron develops the simile he began in the first line by claiming that the beauty of a cloudless, starry night—“all that’s best of dark and bright”—can be seen in his unnamed subject’s face and eyes.
The noun “clime” is another word for “climate,” or weather that is typical to a particular region over a long period of time. Byron indicates that the geographic location of this nighttime scene has a peaceful climate.