An immobile, faintly shimmering barrier springs into existence in a 10-foot radius around you and remains for the duration. Any spell of 5th level or lower cast from outside the barrier can't affect creatures or objects within it, even if the spell is cast using a higher level spell slot. Such a spell can target creatures and objects within the barrier, but the spell has no effect on them. Similarly, the area within the barrier is excluded from the areas affected by such spells.
At Higher Levels. Cast with a 7th-level or higher slot, the barrier blocks spells one level higher for each slot level above 6th.
RollQuest ships the D&D 2014 SRD as a content pack, on a 5e character sheet that does the maths - roll from the sheet and let the numbers work themselves out. Free to start.