If you've created a Facebook page for your business, you can link your online booking there. This gives existing and new customers who see your offers on Facebook the immediate opportunity to book a corresponding appointment at your business.
Add booking to the header of your Facebook page
Facebook gives you the option to insert a prominent button directly in the upper area of your page:

Click the button to add it. You can then specify what action you want your users to take with the button. Choose either "Sign Up" or "Contact Us".

Now you can determine which type of booking you want to integrate. Since the Belbo online booking page is an external website, select this option. Then enter the link to your own booking page (shown as an example in the image).

After saving, your users can access your online booking directly from Facebook.