Pop the air bubble gently using a straight pin or the edge of a putty knife.
Sand excess Spackle away with sandpaper. Wipe debris away with a clean cloth.
Apply more Spackle, if necessary. The air bubble could have left an open hole.
Brush primer over the spackled area to cover the Spackle and allow the paint to better adhere.
Paint the area to camouflage the repair and match it to the rest of the wall.