Catholics? I ask my priest the difference between a mediator and an intercessory but I don't get?

he told me all the saints are mediators because they intercede for us, I am catholic but I don't get the concept because the Bible said the mediator is only between men and God is Jesus christ then what is the role of saints? are they mediators or intercessory? someone answered me mediator is Christ who gives the graces to the saints and saints give the graces to us?