For the commandment is a lamp; and the law is light; and reproofs of instruction are the way of life.
Not too many people can see in the dark. Although some can see pretty well, I have seen others who couldn’t see anything in the dark. But one thing is certain: trying to do something without the proper light always makes the job harder to do; there are more chances of making mistakes.
The more light you have when doing a job, the easier it is to get the job done. When your light is limited it is much harder to tell, even after you have finished the job, whether or not it is done correctly.
King Solomon is letting you know in this verse that God’s truth acts like a light on your path of life. With that Light, the light of God’s word, you will be able to stay on the right path. There is less chance of falling, or going the wrong way.
Not to say that you will never make another mistake. There is the human factor to remember here as well. Meditating or thinking intently on the path and the word are called for as well as staying in the light.
Thinking will make walking that path a lot easier; the same as thinking about what you are doing when you are working in a lighted area will make the job go faster and smoother.
God supplies the Light and leads you in the right path; man/woman must supply the thoughtfulness to travel it well.