A job runs a list of actions when something starts it: an entity event (a record created, changed or deleted), a web event (a request to its URL), a schedule, another job, or a person pressing Run. Each start makes a job run, which records every action’s status and output.
Jobs were called hooks until the admin renamed them, and the code has not followed: the routes are under /cdna-api/hooks/, the records are hook, batch and batchAction, and a web event is called at /cdna-api/webhook/{slug}. Conditions are actions too, so they are read, changed and deleted through the action routes.