Is it safe to use Paypal on eBay? How does it work in terms of transaction?

Two days ago, I’ve won an auction on eBay and I was trying to make a purchase for this item via debit. (This is the first time that I ever bid for something on eBay.) I tried to make the payment several times but it wouldn’t let me. Instead it showed me this following message:
“Your credit or debit card has been declined for this transaction; PayPal could not validate the card. Please validate.”

Then I later realized that the seller only accepts PayPal. I have never used PayPal service before and I’m not so sure how it works. Debit and credit card is all I can used to make the payment. I have no other options. I’m also little skeptical about using Paypal and how it charges or receives money. I was planning to create an account for it sooner so I could still make the payment in less than a week. If not, then I don’t know what kind of trouble that I might face with the seller or the website.

So what are the pros and cons of using Paypal? Could I still be able to delete my PayPal account later on once I’m done using it?

p.s. Sorry if there are some grammar mistakes, I’m in a little rush this afternoon and I have to go somewhere but I’ll be back.