Laman and Lemuel ask, "What meaneth these things which ye have read? Behold, are they to be understood according to things which are spiritual, which shall come to pass according to the spirit and not the flesh?" (v. 1). In other words, they were asking if Isaiah was prophesying about things that are actually going to happen in history, for example when Isaiah talks about the gentiles, the nursing fathers, the isles of the sea, and so on. Are these things to be understood as events in history, or are these abstract spiritual concepts that can apply to any person anywhere? Nephi’s answer is that it is both, as can be seen in how Nephi himself interprets and applies these teaching, both temporally and spiritually. Nephi answers in verse 2 by saying that these things "were manifest unto the prophet by the voice of the Spirit; for by the Spirit are all things made known unto the prophets," so they are spiritual. In verse 3, he explains that "the house of Israel, sooner or later, will be scattered upon all the face of the earth, and also among all nations," so they are temporal. And in verse 4 he states that: "the more part of all the tribes have been led away; and they are scattered to and fro upon the isles of the sea," and so they are also physical or material. All things are known unto the Lord.
Book of Mormon Central, "Where Did Joseph Smith Get His Ideas about the Physical and Spiritual Gathering of Israel? (2 Nephi 21:11)," KnoWhy 290 (March 22, 2017).