A pharmacy is where you go when you need to fill a prescription for medicine. Hospitals have pharmacies, but you can also find retail pharmacies in most cities and towns.
The technique of making medicine and dispensing it is also known as pharmacy, and people who practice this kind of science are pharmacists. If your doctor diagnoses an infection, it's your friendly neighborhood pharmacist who measures your antibiotics, packages them for you, and instructs you on how much and how often to take them. The Greek root is pharmakeia, which means "medicines or cure," but also "witchcraft, spells, or potions."