等待雨是伞一生的宿命等待你是我一生的最求
[dĕng dài yŭ shì săn yī shēng de sù mìng dĕng dài nĭ shì wŏ yī shēng de zuì qiú]
It's an expression of deep dedication and longing. The idea is that just as it is the umbrella's destined role in life to wait for the rain (which implies serving its purpose during the rainy days), I am waiting for you with all my life. It's about being devotedly persistent in love or expectations.