When you jailbreak your device sometimes your device may respring or go into safe mode. Even when you aren’t jailbroken your device might power off or reboot. Most likely you aren’t here to figure out what powering off or rebooting your device is. Most people wan’t to know what their device is doing when it resprings or goes into safe mode.
Power – Simply shutting down your device. The same process is happening when you shut down your computer.
Reboot – Rebooting your device is basically powering it on and then off again. This is often times done to fix issues. If you call Apple and tell them your device is laggy… They more then likely will tell you to shut of your device and turn it back on (reboot) by holding the power and home button at the same time.
Respring – Respring is like refreshing except for jailbreakers. Your homescreen where all your icons are at is your springboard. When you download a theme, tweak, or anything else that can take effect on your device, your device may automatically respring. Respringing is done so the changes in the devices springboard can take place.
Safe mode – Safe mode is a feature of MobileSubstrate that prevents your device from entering a permanent crash cycle by giving you a chance to uninstall malfunctioning extension. without a complete device restore.