In plain English
You can't park or wait here at all — day or night. You may stop briefly to let a passenger out or load if permitted, but you can't sit there.
Where you'll see it
Along main roads, near junctions and anywhere a parked car would block flow or sightlines.
The common trap
Thinking double yellows switch off at night. Unlike single yellows, doubles work 24/7 — no plate needed.
Memory anchor
Two lines = twice as serious. Single yellow has hours; double yellow has none.