In plain English: It lets you look at the raw tree of every single hidden variable in your BIOS and unhide or edit them. Why do manufacturers hide settings? For stability, product segmentation (a cheap board doesn't get voltage controls), or to prevent support calls.
Most modern motherboards and laptops run on firmware. While the graphical interface (the GUI you see when pressing DEL or F2) looks polished, it only exposes about 10% of the actual settings available on the motherboard. aptio v uefi editor
It turns a locked-down, "consumer-grade" motherboard into an engineering sample board. Just remember the golden rule of BIOS modding: Never modify the boot block, and always have a recovery plan. In plain English: It lets you look at