Answer:
In order to get energy into a flashlight, you would need an energy source, which would be most likely a battery in any case.
When the flashlight is off, it is an open circuit, so no energy can make it way through the flashlight and into the bulb. If the flashlight is switched on, it's a closed circuit! The energy can make its way into the flashlight and into the blub, where light is emitted.
I really hope this helped and was in context! Feel free to ask more about it!