I'm afraid the jury's still out on that one.
The following is a list of all elements in Final Fantasy VII Remake. The element of one's attack determines the damage it deals depending on the target's weakness or resistance; if the target absorbs the element of the attack, they gain health rather than lose it.
Lightning tends to work well on machines, making it useful for the proliferation of machines in particular in the early game.
The restorative element is first accessible through Barret Wallace, because as of the downloadable demo, it is utilized by one of his only two magic spells, Cure. Using restorative spells on party members heal them, restoring their HP.