In the first sign, only the sheepskin was covered with dew. It foreshadows Christ, who came as the Lamb of God to take away the sin of the world (John 1:36). He was resurrected by God and received imperishable life as the Firstfruit.
Judges 6
39 Then Gideon said to God, “Do not let your anger burn against me. Let me speak once more. Please, let there be dryness only on the fleece, and let there be dew on all the ground.”
40 And God did so that night, and there was dryness on the fleece only, and there was dew on all the ground.
Conversely
In the second sign, it is the exact opposite. The sheepskin remains dry. Christ’s sacrifice is sufficient once and for all (Rom. 6:10; Heb. 7:27; 9:12). Gideon lays a sheepskin on the threshing floor, but there was dew on all the land. This is a picture of how first Jerusalem (>Israel) and then all nations will share in the blessings of the Firstfruit, Christ. What was once the portion of the Lamb of God alone now belongs to Israel and the whole earth.
Fourth Day
The first sign occurred on the third day, a day connected in Scripture with the resurrection of Christ. The second sign occurs on the fourth day. In the Bible, the number four represents the earth and earthly things. Consider the expression “the four corners of the earth” (Isa. 11:12; Rev. 20:8), a phrase that refers to the entire world or all quarters of the earth. Compare Revelation 7:1, where we find the expressions “the four corners of the earth” and “the four winds of the earth” mentioned together.
This second sign illustrates that Christ is the Savior of the world! (John 4:42; 1 John 4:14)