Perhaps the first thing to understand here is the meaning of the word "revision." I do not know where you are from, but if you have learned British English, this quote may sound strange. In Britain, "revision" means essentially studying something you have already learned to be sure you remember it for an exam. In America, "revision" in this context means looking at writing that you have done and making changes to it where necessary. It is like editing and fixing up an essay.
Once this is understood, the meaning of this quote becomes clearer. What the quote is saying is that revision gives you a chance to fix your mistakes. It gives you a chance to take something that has failed (the spilled milk) and make it into something that is quite good (the ice cream). The general idea of this quote, then, is that the author loves to have the chance to fix the mistakes he or she has made and to make the piece of writing into something that is much better than it had been.