Protection from a player means all of the following: (1) Neither you nor the target permanent can be the target of spells or abilities controlled by the chosen player. (2) Neither you nor the target permanent can be enchanted or equipped by any Auras or Equipment controlled by the chosen players. (Okay, Fortifications too, if the target permanent is a land.) (3) If the target permanent is a creature, it can’t be blocked by creatures controlled by the chosen player. (4) All damage that would be dealt to you or the target permanent by sources controlled by the chosen player is prevented. The same is true for sources owned by the chosen player that don’t have controllers.