For the ship, see: Resistance.
Some ships, station kits, and drones have resistance to certain types of damage. If a ship has energy resistance, any energy shots that hit will have their damage reduced by the percentage value of the resist. This affects recoil damage too; if an immolation is used on a ship with 15% fire resistance, that ship will take 15% less damage from using it. As such, resistances are an important factor in selecting the right ship.
A negative resist value indicates the ship having a weakness to that type of damage; any weapons of that damage type will do increased damage by that percentage value. Resistances can be increased by equipping Diffusers.