Generators are the bread and butter of Love & Pies! You create Generators by merging items like Grocery Lists and Paper Bags until you get a Grocery Bag Generator.
Tapping on any Generator will produce a set of specific items that can be merged. If you tap on a Generator, it will eventually run out of items until it has time to recharge and fill up again. You have the option to speed up this process with Gems.
P.S.: You will know something is a Generator because of its lightning bolt symbol!