A quota is a specific number of things. If a quota is placed on the total number of apples each visitor can pick at an orchard, it means that once you've picked a certain number of apples, you have to stop.
Usually a quota places an upper limit on the total number or amount of some item. There are quotas placed on all kinds of things, like immigrants entering a country, goods exported, or students admitted to a particular school. Quota comes from the Latin phrase quota pars, or "how large a part".
