Scheduled means that something is planned for a specific date and time. If a plane is scheduled to depart at 9 a.m. and it's still sitting on the tarmac at 2 p.m., the passengers may become irate.
You may write a scheduled event down in your daily calendar so you won't forget it — like the meeting you've scheduled with your boss, which you'd better not miss. Airplanes, buses, and trains all have scheduled departure and arrival times, although they may not always leave or arrive on schedule — in other words, they may be delayed. Movies are notorious for starting long after their scheduled times.