| The dismal science|
Supply is generally meant as the supply curve. The curve represents the relationship between prices and the amount of a good or service producers will offer for said prices. As prices go up, producers offer more supply to capitalize on the potential revenues. The point where the supply and demand curves intersect(equilibrium) is where the price of something is determined. Some representations show the long run aggregate supply(LRAS) curve as a perfectly vertical curve that slowly shifts rightward, representing economic growth.
The quantity supplied of something refers to how much of an actual good or service is available at a point on the curve. If demand curve for sugar beets falls, the total supply curve may stay the same but the actual quantity supplied will change.