WHAT DOES IT MEAN TO FEAR GOD?

The reverent fear of The Lord (that is, worshiping Him and regarding Him as truly awesome) is the instruction for wisdom ( its starting point and its essence); and before honor come humility.
Proverbs 15:33 (AMP)

The reverent fear and worshipful awe of The Lord includes the hatred of evil; pride and arrogance and the evil way. And the perverted mouth, I hate.
Proverbs 8:13 (AMP)

The reverent fear of The Lord (worshiping, obeying, serving, and trusting Him with awe-filled respect) prolongs one’s life, but the years of the wicked will be shortened.
Proverbs 10:27 (AMP)