The time for Scheduler Tasks are measured in Ticks. Under normal conditions, there are 20 ticks per second.
Tasks scheduled with .scheduleSyncDelayedTask
will be run on the Main Thread
Bukkit.getScheduler().scheduleSyncDelayedTask(plugin, new Runnable() {
@Override
public void run() {
Bukkit.broadcastMessage("This message is shown after one second");
}
}, 20L); //20 Tick (1 Second) delay before run() is called