Meaning: Celestial bodies that emit light shone with a flickering light with a lot of light in the very large area above the Earth where clouds and stars are seen.
Choice of Words: Stars are celestial bodies that emit light, "twinkled" means shone with a flickering light, "brightly" means with a lot of light, "vast" means very large, and "sky" is the area above the Earth where clouds and stars are seen.