means The light emitted by stars, especially the faint glow they cast on the night sky and the earth below.

from A plain marriage of two old Germanic words — "star" (Old English steorra, kin to Latin stella and Greek aster) and "light" (Old English leoht). Both stretch back through Proto-Germanic into Proto-Indo-European, where the root for "star" is reconstructed as *h₂stḗr. So the compound is exactly what it looks like: ancient words for two ancient things, fused long ago in English.