What does Proverbs 19:9 mean?

This verse repeats the teaching given earlier (Proverbs 19:5), but with a more drastic conclusion. The earlier comment said such a person would not escape; this one says they face death. Repetition, especially in ancient writing, is a deliberate way of creating emphasis. In the most literal sense, the "false witness" is one who lies in a courtroom setting. This is a serious offense, called "perjury" in modern laws. It's also a moral crime—lying about or against other people is a despicable act (Exodus 20:16; Proverbs 6:16–19).

The person who lies in court might suffer penalties, including death in extreme situations. Yet the unredeemed liar is also at risk of divine wrath. Revelation chapter 20 draws back the curtain on the great white throne judgment and allows readers to see what happens to all whose names are not found in the book of life. They are cast into the lake of fire. Revelation 21:8 identifies the kinds of people that will be thrown into eternal suffering. This verse says, "But as for the cowardly, the faithless, the detestable, as for murderers, the sexually immoral, sorcerers, idolaters, and all liars, their portion will be in the lake that burns with fire and sulfur, which is the second death."