bright
昑 centers on brightness or light, likely describing a clear, shining quality.
昑 combines 日 (sun) with 今, which likely provides the sound. The exact historical development is uncertain, but the structure suggests a phono-semantic compound related to sunlight or brightness.
The sun 日 beside 今 suggests the sun shining right now, making everything bright.
For キン, imagine a bright kin (gold) coin catching the sunlight: kin -> キン, and the coin gleams brightly.