PayPal Credit is like a credit card, without the plastic. It's a credit limit that's attached to your PayPal account which you can use for your online purchases.
If your application is successful, PayPal Credit will be available as a funding source within your PayPal wallet and can be used for purchases on argos.co.uk. You can make purchases in the same way as you would with a normal credit card, by choosing PayPal Credit as your funding source at checkout.