Own this product for £7.00 a month (APR 19.9%)?

It means you are buying the product on time and you do so by paying that amount per month until it is paid for. However, for the privelege of paying for it that way they are going to charge you an interest rate of that much per year so you will add that interest rate amount to the 7 you pay for the item.

Thats how credit cards work.