Bank debit cards linked to paypal

Description

Can anyone help to clear up my confusion regarding having a bank debit card attached to paypal. When I checkout using paypal and I select the method of payment, I have been choosing my debit card. Why then is that transaction still showing on the activity statement as a charge (addition) to the balance of my paypal account? I was under the impression that it was taking the funds out of my bank account just like when I use my debit card outside of paypal. Can anyone help me out?