[Q] someone expalin to me ...

...what this means: "Mount and storage > format /system & format /preload"

does it mean that if i format i will lose every single piece of data on my sd card and internal storage? if so why is this recommended because i imagine it would wipe out the zip that is stored either on external or internal storage, how would i proceed to flash in that situation? is it safe to format mount and storage without worrying about data such as zips and folders that conatin large game files?

please give me a detailed explanation

thanks in advance