The following is a list of all elements in Final Fantasy VII Rebirth. The element of one's attack affects the damage dealt based on a target's weakness to that element or a resistance to it. Targets can also be immune to or absorb damage from an element. Several 
Magic Materia also have one or multiple elements tied to them, which can be paired with 
Elemental Materia on a party member's weapon to imbue their attacks with the element, or on armor to resist against it.
Fire[]
Fire can be used by party members with the Fire Materia or the Fire and Ice Materia equipped.
Fire is effective against most of the human enemies, save for a few bosses.
Ice[]
Ice can be used by party members with the Ice Materia or fire and ice materia equipped.
Ice is effective against most of the biological enemies, save for a few bosses,
Lightning[]
Lightning can be used by characters with the Lightning Materia or Lightning and Wind Materia equipped.
Lightning is effective against all mechanical enemies, including bosses.
Wind[]
Wind can be used by characters with the Wind Materia or lightning and wind materia equipped.
Wind is effective against most of the flying enemies, save for a few bosses.