Using a Magic action to read the scroll creates a 5-foot Emanation [Area of Effect] originating from you. For 5 minutes, Undead can't enter or affect anything in the area. However, if you move in such a way that an Undead would be inside the area, the effect ends.
As a Magic action, a creature within 5 feet of the Emanation [Area of Effect] can attempt to overcome it, which forces the creature to make a DC 15 Charisma saving throw. On a successful save, the creature ceases to be affected by the Emanation [Area of Effect].