Runed Halo gives you protection from each object with the chosen name, whether it's a card, a token, or a copy of a spell. It doesn't matter what game zone that object is in.

You can still be attacked by creatures with the chosen name.

You'll have protection from the name, not from the word. For example, if you choose the name Forest, you'll have protection from anything named "Forest" -- but you won't have protection from Forests. An animated Sapseep Forest, for example, could deal damage to you even though its subtype is Forest.

You can name either half of a split card, but not both. You'll have protection from the half you named (and from a fused split spell with that name), but not the other half.

You can't choose [nothing] as a name. Face-down creatures have no name, so Runed Halo can't give you protection from them.

You must choose the name of a card, not the name of a token. For example, you can't choose "Saproling" or "Voja." However, if a token happens to have the same name as a card (such as "Shapeshifter" or "Goldmeadow Harrier"), you can choose it.

You may choose either one of a flip card's names. You'll have protection only from the appropriate version. For example, if you choose Nighteyes the Desecrator, you won't have protection from Nezumi Graverobber.