You use it very much like a tea kettle. It pulls a thousand Watts for 3 to 5 minutes depending on what you're cooking. You bring the water to the boil and you are pretty much done. You only leave it plugged in while you're using it you must use it with water in it and you always unplug it when you're done.

I should note that the one that I linked before was the same design but with inferior materials and leaked badly, shorting out and causing a dangerous situation. I linked to the replacement that I've been using since that has been performing very well.

https://www.amazon.com/gp/aw/d/B07BN67KJM

If you're using something or electrical to cook, and a device like this is ideal because the heating element is almost directly in contact with the material that's being heated so the amount of energy loss is very low and the efficiency is much higher. Just about the only way you could do better is with an induction cooktop which turns the pot itself into a burner using induction.

I can't speak to generator usage.