Paypal is kind of online mediator for you, a payment processor also.
With paypal, you can send money from your credit card to paypal account and from there send it to any other paypal holder. You can also receive money from others. You can use it payment processor on your website and can sell product. People will make payment, it will come in your paypal account, from there you can transfer it to your bank account. For all this services, paypal deduct small commission generally from all payment you receives.
