What does Proverbs 4:18 mean?

Symbolism about walking, or paths, is common in Scripture. The general idea is that evil creates a dark, jagged road which causes people to be lost, or to fall. Truth and godliness are compared to bright, straight, safe roads. As stated here, following godly wisdom is like walking on a road lit by light of dawn, brighter and brighter until it bursts into full day.

This is especially appropriate, since Jesus, the sinless Son of God, is defined as "the true light" (John 1:9). He called Himself "the light of the world," and said, "Whoever follows me will not walk in darkness, but will have the light of life" (John 8:12). The apostle Paul addressed the believers at Ephesus as "light in the Lord" and exhorted them to "walk as children of light" (Ephesians 5:8). The apostle John wrote that "God is light, and in him is no darkness at all" (1 John 1:5). He added, "If we walk in the light, as he is in the light, we have fellowship with one another, and the blood of Jesus his Son cleanses us from all sin" (1 John 1:7). As believers walk in the light, others see our good works and glorify our heavenly Father (Matthew 5:16).