997 B
For if their rejection means the reconciliation of the world
"For if because God rejected them, he will reconcile the rest of the world to himself"
their rejection
The pronoun "their" refers to Jewish unbelievers.
the world
Here "the world" is a metonym for the people who live in the world. Alternate translation: "the people in the world" (See: rc://en/ta/man/translate/figs-metonymy)
what will their acceptance be but life from the dead?
Paul asks this question to emphasize that when God accepts the Jews, it will be a wonderful thing. You can translate it in an active form. Alternate translation: "how will it be when God accepts them? It will be like they have come back to life from among the dead!" or "then when God accepts them, it will be like they have died and become alive again!" (See: rc://en/ta/man/translate/figs-rquestion and rc://en/ta/man/translate/figs-activepassive)
the dead
These words speak of all dead people together in the underworld.