PRL atlicles and software are pre-written and either sold or given away. Once you obtain rights to the product they are yours and you can do just about anything you want with them.
You can find PLR for just about any subject you can imagine. Some are free and some you have to purchase.
If you have a website, blog, or send out a news letter PLR articles are a great way to to provide fresh content for your readers.
One of the best paces I've found for providing free quality PLR articles and software is PLR Wholesaler. The list of items you can download is huge and updated regularly
If you are interested or curious check it out, as I said, it's free and there's no membership fees ever.
One word of advice. Don't confuse "Private Label Rights" with "Master Label Rights". There's a different set of rules for each. Master Label Rights normally have limitations what and how they can be used.
I know you can't wait to see everything for yourself!