The Savior was the One. This is consistent with the next verse as there were twelve (apostles) others who were following him.
"I love the Book of Mormon most of all because it has led me to a fuller understanding of the life and mission of Jesus Christ and has opened my heart wider to experience His love. The Book of Mormon testifies of Christ from the very first chapter, where Lehi sees 'One descending out of the midst of heaven [whose] luster was above that of the sun at noon-day' ("1 Ne. 1:91 Nephi 1:9), to the very last chapter, where Moroni says, 'If ye by the grace of God are perfect in Christ, and deny not his power, then are ye sanctified in Christ by the grace of God, through the shedding of the blood of Christ, which is in the covenant of the Father unto the remission of your sins, that ye become holy, without spot' ("Moro. 10:33Moroni 10:33). Through the many testimonies of Book of Mormon prophets and through Christ's own words to the Nephites, I have come to exclaim, as does Nephi, 'I glory in plainness; I glory in truth; I glory in my Jesus, for he hath redeemed my soul from hell.' ("2 Ne. 33:62 Nephi 33:6; italics added.)
"I love the Book of Mormon. And I love the Lord for sending it to bless our lives." (Robert A. Rees, Converted to Christ through the Book of Mormon, edited by Eugene England, p. 198.)