What is meant by the following:

Electrode potential for M3+/M

Is it standard oxidation potential (SOP) or reduction potential (SRP)? What does a high positive or negative value for SRP and SOP tells us about the reactivity of the element?

You see this electrode potential signifies the potential of the reaction that means the potential of methyl 3 plus to change into metal that means if it is positive it has high potential to change to metal that means it is highly reactive in the sense that it spontaneously changes to metal that means it gets reduced easily or you can say that it's and good oxidizing agent so whenever you see a positive potential that means that conversion has a positive tendency that means when you compare them those having negative potential for same reaction will be less spontaneous then those having positive potential