When the Lord recovers his people, he gathers them, protects them, and reestablishes his covenants with them. The reference to “the second time” implies that there was a first time that the Lord set his hand to recover the people.
LeGrand Richards
“From this scripture we learn that the events described were to be in the future: ’The Lord shall set his hand again the second time to recover the remnant of his people.’(2 Nephi 21:11) There could not be a ‘second time’ unless there had been a first. The first time was when the Lord led Israel out of Egyptian bondage and captivity.” (A Marvelous Work and a Wonder, pp. 202-3)
“My Words Shall Hiss Forth Unto the Ends of the Earth for a Standard Unto My People”
Most of the time when the scriptures speak of the ensign lifted up in the last days, it refers to the Church of Jesus Christ of Latter-day Saints. In this particular passage, Nephi uses the language of Isaiah to describe the Book of Mormon hissing forth unto the ends of the earth. Therefore, the Book of Mormon is, in part, the ensign spoken of by Isaiah, And he will lift up an ensign to the nations from far, and will hiss unto them from the end of the earth (Isa 5:26). The many other meanings of this passage are explained by Elder McConkie.
Bruce R. McConkie
“Many ancient prophecies foretold that in the last days the Lord would set up an ensign to the nations, a standard to which Israel and the righteous of all nations might gather. (Isa. 5:26; 11:10-12; 18:3; 30:17-26; 31:9; 49:22; 62:10; Zech. 9:16.) This ensign is the new and everlasting covenant, the gospel of salvation (D. & C. 49:9); it is the great latter-day Zion (D. & C. 64:41-43); it is The Church of Jesus Christ of Latter-day Saints.” (Mormon Doctrine, p. 228)