绿 is a simplified form of the traditional character 綠, which is a phono-semantic compound of semantic 糸 “silk” and phonetic 彔 (lù 🔊). But what does silk have to do with colour green? Lawrence J. Howell writes in his Etymological Dictionary of Han/Chinese Characters:
As per 彔 (pare/strip bamboo) + 糸 thread → threads dyed the vivid color of bamboo freshly stripped of its bark → green → light green.
In Japanese, 綠 is pronounced midori. Apart from meaning colour green, Midori is a popular female given name.