Schedules (job header button) starts a job on its own, on a recurring day/time pattern -- a named weekday, weekday/weekend, a day-of-month, first/last of month or year, or a plain daily window, each with how often to repeat inside it and what to do if a run overruns or the window gets missed entirely. A job can also be marked to fire once, every time the Worker service (re)starts, on its own or alongside a real schedule -- useful for catching up on whatever a restart's downtime otherwise would have missed.
A job can be started by a schedule or a file-watch Start trigger, never both -- Schedules disables itself with an explanatory tooltip the moment a Start-scope gate is already attached.
See job-scheduling.md for the full technical story.
See also: Glossary for related terms.