Consider this analogy. Have you ever tried to put a wrinkled dollar bill into a soda machine? You try your best to straighten it out but the machine simply can’t receive it in its wrinkled, tattered state. But if you put in a crisp, new bill, the machine takes it no problem. Purgatory is where all the “wrinkles” are purged and “ironed out.” Remember, the wrinkled dollar is not worth less than the new one it just needs some help.
Put simply, Purgatory means you’ll get to heaven some day, but that you have a few things God has to “iron out” first.