At the heart of these three letters is brightness, the blaze of the sun at its height. From that one image Hebrew draws several words. The brightest hour of the day is noon; a hole that lets light in is a skylight or window; and to make a thing publicly clear is to declare it. Light, midday, and clarity of statement are one idea seen through different windows. Every word is verified against pealim, niqqud included.
The same root runs through the verb system. Each binyan is a voice: it bends the one idea into active, passive, causative or reciprocal. Tap to hear.
Only the causative hif'il is lexicalized as a verb: to declare is literally "to make bright / make clear", to bring a statement into the light. The plain verb of shining is archaic and unused; the root now lives mainly in its nouns.
Same root letters, different noun moulds (mishkalim). The mould tells you the function: who does it, the act of doing it, or the thing produced.
Strip the prefixes, suffixes and vowels. Three consonants remain, and the meaning lives there.