They are most commonly a cross between a female blood parrot and a male pink convict from what I've read. Some people say they don't get quite as big as Blood Parrots, which in time can get fairly large, but with so much conflicting information on hybrids I've seen, go larger than what you expect as far as tank size. IME they aren't quite as people responsive nor as aggressive as Blood Parrots. Generally the same rules that apply with convicts apply with jellybean parrots.
Some jellybean parrots are actually nothing more than a dyed Blood Parrot, and NOT the Con/Parrot cross. I reccomend you stay away from these.