“Light” in the Bible represents divine truth, ideas which pour out to us from the Lord's infinite love. It makes sense, then, that when something “shines” in the Bible, it means it is filled with that truth and inspired by it, and is itself offering ideas that are derived from that truth. For instance, when Moses spoke with the Lord, his face shone afterward, so brightly that he wore a veil; this shows the divine inspiration that went into his writing of the law for the Children of Israel, writing that is filled with divine truth.

'To shine' or 'shining' can also mean being exempt from falsity, or being pure by reason of truth.

(References: Apocalypse Explained 1222; Apocalypse Revealed 53, 414, 897; Arcana Coelestia 10703)