Sugar soap is a very caustic and powerful cleaner (at a guess it's got some caustic soda/washing soda/sodium hudroxide in, but I dont know). You use it for cleaning paintwork in kitchens which gets grease on from cookers, and so on. There are also products sold in Body Shop type places called "vanilla and melon sugar soap" and so on, which are exactly what they say. It is obviously important to be clear which product you've got before you start using it, otherwise you might end up kind of blotchy.