What does the pond do?
The pond allows you to buy Lolligators for 1200 candies each. Lolligators can be fed candies, turning them into lollipops at a 1:1 ratio.
It's useful if you have a large amount of candies and want more lollipops instead.
The pond, when bought, allows you to buy "Lolligators," or alligators who eat your candies in exchange for lollipops.