Basically, it is just telling you that there is an error in the folder - it doesn't give much of a clue as to what the error is, but since its junkmail, its not important.
You should empty the junkmail (2) folder - something in it is causing the sync error. Actually, you probably should delete it too (and a (1) folder, if it exists), then empty deleted items (or delete it from web access) - the (2) indicates its a duplicate folder.