It is always a good idea to pay close attention to signs that start with “ra-wang”. It means “be careful”. The second word is “rot” which usually refers to cars but also to all vehicles in general. In this case it is motorcycles. The last word is “suan” which you may recognise as garden or park. However, here it means “passing in opposite directions”. So be careful of vehicles going both directions.
ระวัง รถ สวน (ra-wang rot suan)