On a moonlit night in He Lang, songs move in the cold Sichuan.

First of all, I want to point out that it is "Lang Lang" rather than "He Lang". Juan refers to a person's face, which is red. These are the last two sentences of a poem. The first two sentences are "The fire shines on the heavens and the earth, and the red star is in chaos."

This is an ancient poem describing a smelter (who was smelting copper at that time). In short, it means, "Fire lights up the world, a little spark is generated in the smoke, and red-faced young smelters (strictly speaking, not workers) reverberate in the cold mountains and rivers on a moonlit night." The word "move" in the poem means "shake".