Wife wants to use ebay to sell stuff, how does PayPal work

I have had an ebay account for a long time but haven't used it in years

When they made some changes I decided I didn't want to update the info they wanted. Now that she is wanting to sell some of her collectibles and some of mine need to go have thought about getting it updated

So can anyone tell me how pay pal works since that seems to be the way everyone likes to pay.