Shipping costs
What it costs you to ship, by method and by shipping class, as opposed to what the customer paid for shipping.
WooCommerce records what the customer paid for shipping. Profitrics needs the other number: what the delivery cost you. The two are rarely equal and the gap is often where a thin margin goes.
The baseline
The default shipping cost applies to any order whose method has no rule of its own. It ships as 0.00, which reports every delivery as free to you, so this is worth setting even to a rough average.
By shipping method
Each shipping method you offer can carry its own cost. The one to check first is free shipping: the customer paid nothing, so without a rule here the order looks like it cost nothing to fulfil, which is exactly backwards.
By shipping class
Shipping classes let cost follow the product rather than the method, which is what you want when one product is bulky, fragile or heavy enough to change the postage on its own. A class cost applies on top of the method rule.