Should I "Clear Cashe" in my Samsung phone apps to save my battery - wth is "Cashe" anyway?

Cache is a temporary storage where your apps download files so that they can be quickly used in the future.
Apps like FB cache images and text so you can still somewhat use the app when you're off line.

As for it saving battery, I don't think it will help much. It will free up some space, but your apps will rebuild their cache as needed.

Note that the correct spelling is "cache".

It is a form of temporary storage.

Most or all of what is in it should be disposable.

Clearing it Won't extend the time between battery charges.