The Branch likely refers to the remnant (the faithful people who remain) who would form Israel’s new beginning after the exile (see Isaiah 6:13). Some understand the branch as the ideal descendant of David, the Messiah (God’s chosen king; see Isaiah 11:1; Jeremiah 23:5; 33:15–16; Zechariah 3:8; 6:12).
Isaiah describes a beautiful and glorious change. The people had experienced shame and disgrace (Isaiah 3:17–25). Now they would experience fertility (fruitfulness) and beauty. This change would show God’s presence and blessing among the remnant (4:6).
Even the land would change. The fruit of the land and nature itself would move from desolation (emptiness and ruin) to glory. Isaiah compares this future to the garden of Eden (see Isaiah 51:3; 65:22). The message of renewal finds its ultimate fulfillment in the new creation (see Romans 8:19–27; 2 Corinthians 5:17; Galatians 6:15; Ephesians 2:15; 4:24; Revelation 21:22–27).
Those who survive in Israel (the remnant) would be the true citizens of Zion. They would belong to the renewed people of God and share in his promised restoration.