A sweet, sticky candy usually on the end of a plastic/ paper stick. Comes in many flavors, there's raspberry, watermelon, root beer, banana split, grape, cherry, blue raspberry, cotton candy, etc.
If you ever hear them referred to as "dum dum's", that's a very popular lollipop brand. When talking about dum dum's lollipops, people usually will just call them dum dum's.
I personally find them a little too sweet, but eh.
That sure is one sweet lollipop.