Resistance is indicated in the Noise Report, and can range from 0% to 200%.
If the resistance rate is 200%, then the Noise will absorb the attack's damage. This is indicated by green numbers showing health gain rather than health loss.
If the resistance is more than 100% but less than 200%, then the damage will be reduced. This is indicated by ordinary white numbers preceded by the symbol of either negative or positive psychs.
If the resistance is exactly 100%, then the Noise has no resistance or weakness to the element, and damage output is relatively normal. This is indicated by the normal white damage numbers preceded by no symbol.
If the resistance is less than 100%, then damage from that psych element will be super effective and deal greater damage than what it would deal if the same Noise had a higher resistance. In this case the damage will be indicated by yellow numbers preceded by the symbol for positive or negative psychs.