I'm not the person you were asking, but:

Cash back credit cards reward you by refunding a percentage of your purchases made using the card. You can use this refund as a credit towards your monthly balance or as cash deposited into your bank account. Some cards offer a flat percentage on all purchases, while others offer higher percentages on select categories.

Source: https://www.ratehub.ca/blog/best-cash-back-credit-cards-in-canada/

Of course, they wouldn't be doing this if you weren't paying them at least the refunded amount somewhere else - through fees, or through people's average interest payments, or through price increases applied by the stores to cover the fees they pay to the credit card companies.