PayPal is an online payment gateway for merchants to collect online payment from their customers.
After submitting their order on your online ordering platform, customers will arrive on the PayPal payment page. Customers can choose to pay using their PayPal account or through their credit/debit card without a PayPal account.
Once the payment goes through, the money is stored in merchant's PayPal account. You will receive an email notification from PayPal. You can then withdraw your money from your PayPal account to your bank account that can be linked to PayPal.