Could you explain how glucose is co-transported across the wall of the small intestine with sodium, please?

The purpose of glucose and sodium being transported across the epithelial cells of the small intestine is in order to move glucose across the cell against its concentration gradient. Because these two substances move together, it means that Na+ can move down its concentration gradient while moving glucose against its concentration gradient.
A low concentration of Na+ is maintained within the intestinal epithelial cell by a sodium-potassium pump (uses active transport) which pumps Na+ out of the cell and into the blood whilst drawing K+ into the cell from the blood. The movement of blood through the capillary ensures that the concentration of Na+ here remains low and so Na+ continues to be pumped out of the cell. To rectify this drop in Na+ concentration within the epithelial cell, Na+ is moved passively into the cell via the Na+/glucose cotransporter along with glucose. This movement happens from the lumen of the small intestine into the epithelial cell. This increase in glucose concentration within the cell means that there is a concentration gradient of glucose between the epithelial cell and the blood in the capillary so glucose moves down its concentration gradient from the epithelial cell and into the bloodstream.