素颜姑娘从不怕雨淋
[sù yán gū niáng cóng bù pà yŭ lín]
Literal translation would be 'A Plain-Faced Girl Is Never Afraid of Getting Rained On'. 'Plain-faced' often refers to girls who are brave enough to show themselves naturally without makeup. And 'not afraid of getting rained on' means boldness and courage in dealing with difficulties.