月亮代表我的心我的太阳就是你
[yuè liàng dài biăo wŏ de xīn wŏ de tài yáng jiù shì nĭ]
It is partly derived from a Chinese pop song titled 'The moon represents my heart', conveying a very deep love towards someone, implying this special one brings the sun-like warmth to the user, while the moon (which usually evokes thoughts of cool serenity) symbolizes another aspect of love.