Vegetable shortening is a solid fat made from hydrogenated vegetable oil, and is often used either as a substitute for lard or butter in baking recipes, or to grease pans. Look for it sold at your supermarket in cans or sticks; choose a brand that contains no harmful trans fats.
Measure shortening by packing it into a measuring cup and leveling it with a knife, or use the water displacement method: If you need 1/2 cup shortening, fill a measuring cup with 1/2 cup water, then add shortening until the water reaches the 1 cup mark, and drain off the water.