What does it mean that he who speaks forth the word of God speaks unto men to edification, exhortation, and comfort?
Speaking forth the Word of God means edification, exhortation, and comfort: it builds people up, supports them, encourages them, and comforts them. It lifts them up and exhorts them. Since the world is under the curse and many are hurting, the best comfort is proclaiming God's Word to them.
Les explains that the gift believers should really long for is the gift of speaking the Word of God, and this is the number one criterion. He reemphasizes in verse 3 that the one who speaks forth the Word of God speaks unto men to edification—to lift them up, support them, exhort them, encourage them, and comfort them. Because we are in this old world under the curse and many people are hurting, the best way to comfort them is by proclaiming the Word of God.
But he that prophesieth speaketh unto men to edification, and exhortation, and comfort.