校花是需要浇水的校草是需要除草的
[xiào huā shì xū yào jiāo shuĭ de xiào căo shì xū yào chú căo de]
"Flowers on campus need watering, grasses on campus need weeding", this metaphorically describes that beautiful girls (called flowers on campus) require careful attention and care to maintain beauty and charm; meanwhile boys (referred to as grasses on campus here) should constantly work on self-cultivation to be better.