Answer:
Glycolysis is the metabolic pathway (process) that converts one molecule of glucose into two molecules of pyruvate. In the process the pathway forms two molecules of ATP and one molecule of NADH from two molecules of ADP and phosphate and one molecule of NADH.
The importance of glycolysis is that it provides the cell with a small amount of readily accessible energy in the form of ATP and it provides the mitochondria with a source of pyruvate. There, the pyruvate can be completely oxidized to CO2 and H2O and form a large amount (~28 molecules) of ATP from ADP and phosphate. More importantly, it provides red blood cells with there only source of ATP (since they have no mitochondria).
