Many countries have more than one tax type, this area allows you to set them up and even make the most common one your default
Click on Add Tax Rate
Name the Tax
Put in the tax rate percentage
If you use Xero you will see the Xero box, click in and you will see the Options that are th Xero codes, pick the one that is relevant
If this is the most common tax rate that you use you can click on Default. Note: The default one is always used if any pricing lines have the tax rate blank
Click on Submit
Now when you set up a new Pricing it will ask you to select the tax type you want to use.