This is the resistance between electrodes that is required for the 61F Floatless Level Controllers and K7L Liquid Leakage Sensors to operate. The 61F and K7L will definitely operate when the liquid or solid inter-electrode resistance value is lower than the operation resistance value.
Reference:

The higher this value is, the easier it is for the Level Controller to operate even with low-conductivity liquids, thus raising the sensitivity of the Level Controller.