This is an advanced setting that allows you to specific a fixed price for each combination of options available for a product. For example, a product might be available in two different widths, and three different heights. Normally with options, you can only set a price modifier for each option independently from other options. So for example, you could set that the taller item is +£10 in cost, but in practice the amount extra will need to vary depending on the width of the item too.

By setting the 'usecombinationprice' object config on, you can price the individual combinations you create for a product without this being calculated by the base price plus/minus any option price modifiers.