When you load the menu option, the values you see displayed will be the values currently in use by your game. Vanilla values are 3.3 and 2.0. If the menu is displaying different values, then you have a mod installed which is already adjusting these two settings. If you choose to select a new setting, Trade & Barter will override the settings from the other mod. If at any time you wish to revert the settings back to those made by another mod, simply deselect this setting and reload your game. You will need to reload your game before the changes from Trade & Barter are fully canceled out.
In trade, barter (derived from baretor) is a system of exchange where participants in a transaction directly exchange goods or services for other goods or services without using a medium of exchange, such as money. Economists distinguish barter from gift economies in many ways; barter, for example, features immediate reciprocal exchange, not delayed in time. Barter usually takes place on a bilateral basis, but may be multilateral (i.e., mediated through a trade exchange). In most developed countries, barter usually only exists parallel to monetary systems to a very limited extent. Market actors use barter as a replacement for money as the method of exchange in times of monetary crisis, such as when currency becomes unstable (e.g., hyperinflation or a deflationary spiral) or simply unavailable for conducting commerce.