ID is the job's id, and the id the cancel route takes. The dispatcher sets it equal to the render's prompt id, so it is the same value the studio knows the job by.
Label is the cheap human name for the render — the output filename prefix lifted out of the submitted graph. Empty when the graph carried none. The graph itself is never in this list; the tasks describe endpoint serves it.
Status is the job's lifecycle state: queued, running, completed, failed or canceled — plus "stalled", which is this surface's own reading of a job that is STARTED whose worker died: its lease has elapsed and no reaper has taken it back yet. Without it such a job reads "running" forever. An engine state this surface does not recognize passes through lower-cased rather than being coerced into one of these.
Worker is the node that actually CLAIMED the job, which is not always the one it was aimed at: a shared-lane job has no GPU but does have a Worker once picked up. Empty while the job is still waiting.