Behold, here cometh the Dreamer What will become of his dreams ?- What does that mean?

Woodles has already explained the meaning with reference to context. But even without reference to it the sentence makes sense. It is addressed to a person who is a dreamer and is alway lost in this. He may or may not be doing anything to realise those dreams. If the former the reference to him as dreamer is rather a derisive. However, if you are aware that his dreams are quite high and despite his devoting to realise them he is not seem to succeed the above announcemet will be rather symspathetic.