The sign of Immanuel in Isaiah 7 is a promised child whose name means God with us. In Isaiah's setting, the sign addresses Judah's fear during a political crisis and points to God's presence and faithfulness.
King Ahaz faces pressure from surrounding powers, and Isaiah calls him to trust the LORD rather than panic. The Immanuel sign is given in that crisis. Later biblical interpretation sees the theme of God with us reach its fullest meaning in Jesus, but Isaiah's immediate context should still guide the answer.
This question teaches readers how Bible & Context handles prophecy: immediate setting first, then canonical fulfillment without shortcutting the original passage.
14Therefore the Lord himself will give you a sign: behold, a virgin shall conceive, and bear a son, and shall call his name Immanuel.