A quota was a goal for a certain number of something to be achieved.
In 2152, a number of Tessic's species operated a ramshackle deuterium mining colony on an isolated planet. Their production of deuterium was subject to quotas. (ENT: "Marauders")
During the Eminiar-Vendikar War each side was required by treaty to send a quota of individuals to disintegration stations in accordance with casualties determined by computer projections. Failure to meet quotas was considered a severe breach of the treaty. (TOS: "A Taste of Armageddon")
In 2255, after Christopher Pike encouraged him to enlist in Starfleet, James T. Kirk laughed at the notion, saying Starfleet must be down on its recruitment quota for the month. (Star Trek)
The Janus VI pergium production station had production quotas as of 2267. (TOS: "The Devil in the Dark")
According to Dukat, in his first official act as Prefect of Bajor he ordered all labor camp commanders to reduce output quotas for workers by fifty percent. (DS9: "Waltz")
On Terok Nor in the mirror universe, failure by Terran slaves to meet a production quota could be punishable by death. (DS9: "Through the Looking Glass")
Nocona's asteroid mining operations in 2378 were also subject to a quota. (VOY: "Homestead")