天黑下来你就是我的光
[tiān hēi xià lái nĭ jiù shì wŏ de guāng]
'When Dark Comes You Are My Light', conveys that even during hard times you always get support, comfort or guidance from certain people who become hope for oneself; they light up one's life when days look dark. It also has a warm, emotional tone expressing deep affection and dependency.