What does sugar and spice and everything nice mean?

Goes back to an old nursery rhyme.  "What are little boys made of, what are little boys made of?  Snips and snails and puppy-dog's tails, that's what little boys are made of."      "What are little girls made of, what are little girls made of?  Sugar and spice and everything nice, that's what little girls are made of."  Google "snips and snails" for more.