The photo is not very clear, but I think it is clear enough to understand the message. For reasons that we don't quite understand people are "discouraged" from walking on lawns. Sad in a way as our feet only get to plod on cement or rock paths, and tiles indoors.
This message was on a tree at a museum I went to today. Perhaps this will help some folk understand why there is so much "Chinglish" - it is not easy to directly translate from Chinese to English and make sense at the same time.