Starch is an organic macro-molecule consisting of carbon, hydrogen and oxygen atoms. It is a polysaccharide consisting exclusively of glucose molecules. When it is digested by the enzyme amylase, it breaks down into its monomer building blocks which are glucose molecules. Glucose is considered to be a simple sugar which can be transported by the bloodstream to cells which require the energy stored within its chemical bonds to perform cellular work.
A polysaccharide like starch can have hundreds or even thousands of glucose sub-units held together by glycosidic linkages. Plants produce starch as a way to store energy until it is needed. Animals can consume plants and the starch can be chemically digested making the glucose molecules available for the animal's energy needs.
In conclusion, starch is broken down chemically by the enzyme amylase to simple glucose molecules.