What is the function of small intestine?

Mainly for absorption.

Small intestine consists of small finger like projections called Villi which are mainly adapted for absorption.When the pancreas produces the pancreatic amylase,lipase,protease (trypsinogen)as well as the intestinal glands also secretes the juice containing enterokinase,erepsin,maltase,sucrase.These enzymes works on the . and fats.later on after digestion amino acids and glucose are absorbed in the blood capillaries of villi and anf fatty acids and glycerol are absorbed in lacteal in the villi.