What does Proverbs 31:18 mean?

Many depictions of the excellent, godly wife (Proverbs 31:10) include diligence and responsibility (Proverbs 31:13, 15). Both literally and symbolically, she is depicted as bringing in necessary supplies (Proverbs 31:14) and making good business decisions (Proverbs 31:16). Here, "profitable" work is again commended. That is connected to the continued burning of a lamp: a symbol which implies foresight, planning, and sustained success.

Keeping one's lamp burning at night can be a metaphor for hard work (Proverbs 31:27). It also implies planning: to keep the light burning, it needs to be supplied with oil. This was part of the lesson in Jesus' parable of the ten virgins (Matthew 25:1–10). Diligence means planning such that needs are met. If a lamp goes out at night, it results in darkness. The godly woman looks ahead, so her family is supplied and cared for during hard times.