Fees are an additional amount added to the subtotal, before tax calculations.
They can be used to calculate an amount for a specific service automatically. The fee amount would be a percentage of the amount on what is sold (e.g. insurance, service, etc.).
Fees would apply to all the line items present on the pricing table, unless you specify that you want to exclude specific line items from the calculation. This help article shows you how to exclude items from fee calculation.
Exclude a line item from fee calculation from the pricing table
From the pricing table, you can indicate an item should not contribute to the fee calculation.
Like on the screenshot below, reveal the options, then uncheck the box next to the fee name.
The line item will be flagged as "Fee exempt" with a small label next to its name.
Exclude a product from fee calculation by default
If you find that excluding products or services from fee calculation is time-consuming, you can specify from the catalog that they should not be included in the fee calculations by default.