The function of the Golgi apparatus in a cell is to modify, sort, and package proteins and lipids for secretion or delivery to other organelles. Proteins synthesized in the ribosomes are transported to the Golgi apparatus, where they undergo post-translational modifications, such as glycosylation. The Golgi then sorts these molecules and packages them into vesicles for transport. This organelle is essential for the cell's ability to process and distribute crucial biochemical compounds.