The Payment section allows you to set up the possible payment gateways.

Here you can enable/disable the option called Pay locally, meaning that customers will have to pay for the services at the office.

When submitting an appointment customers can mark this option if they are planning to pay offline.

Other payment options include Stripe, WooCommerce, PayPal.

Please note these options are part of the premium addon you need to buy separately. Follow this article to learn more.