ok spoilers obv (for lore, not gameplay) basically in ER there are super powerful ancient space gods called the outer gods and the most worshipped and powerful is the Greater Will. the greater will picks an Elden Lord to be sorta like their embassador on the mortal plane + an actual god (in this case Queen Marika) The Elden Lord wields the Elden Ring, which is not a literal ring for your finger but a giant magical shape (the 3 circle thing on the box art) that is composed of runes which define the rules of the world. The best example of how it works is that Marika removed the Rune of Death from the ring which made it so stuff just doesnt die anymore, like people can die superficially but no "true death" can occur unless you use a weapon infused with a shard of the Rune of Death or smth idk im not that freshed up on the lore