This menu lets you define the amount of damage this hero takes from different elemental attacks. The actual in-game values also depend on the equipment which the hero is wearing. See the General Game Data ->Battle System Options ->Elemental Resistance Calculation menu Help file for more information.

Set the values by typing them in. You can enter fractional values too, by typing a decimal point (Period).

Press Minus to negate a value. If a hero takes negative damage from an element, then they will be healed.