Two completely different uses. (1) As a printing radical
艹 ('grass top',
草字头) sits atop
花,
草,
茶,
菜 and many plant-related characters. (2) On the Chinese internet
艹 is a censor-friendly stand-in for the homophone
操 (cào, 'fuck') — a pseudo-polite exclamation of shock or admiration. The internet sense is mildly vulgar, much milder than
操 itself.