This prophecy, taken out of Paul's writings in Romans, speaks of a time after the rapture, and extending all the way through the Tribulation, in which Israel will return to God and be saved, finally realizing that Jesus, whom they've long rejected, is really their Messiah.  It is believed that only a small remnant of those alive at the beginning of the Tribulation will make it alive to the end, and of those who do, all of them will be saved.