Hello community!

I'm playing a orc warrior (defensive) or may aswell call it Tank. And I noticed this fascinating perk called Magic Resistance (Rank 1-3), that blocks 10% of a spells effect (Rank 1-3 10/15%/20%?).
Does this mean it it blocks 10% of the spell dmg that I take or 10% of effect such as frost breath (Frost dragons for example) that reduces my movement speed for a small time? Or what this means. I'm not Ub3r good on english so would be nice if I get a clarification for this perk.

Thanks