The fear of the Lord is the maxim of the book of Proverbs: the quest for wisdom begins with the fear of the Lord.
What does it mean to fear the Lord?
In Proverbs 1:1-7, we are instructed to know wisdom and instruction, to understand words of insight, to receive instruction in wise dealing, in righteousness, justice, and equity; to give prudence to the simple, and knowledge and discretion to the youth. We are told to let the wise hear and increase in learning, and the one who understands obtain guidance, to understand a proverb and a saying, the words of the wise and their riddles. And then we are told that the fear of the Lord is the beginning of knowledge, but fools despise wisdom and instruction.
The wisdom offered here is practical (instruction in wise dealing), intellectual (increasing in learning), moral (righteousness, justice, and equity), and probing (to understand a proverb and riddle). It is for all people, be they naive or ignorant (the simple. . . the youth) or already experienced (let the wise hear).
The great virtue of the book of Proverbs is that it seeks to instill teachability, the willingess to grow in wisdom no matter how far along a person already is.