It means to respect Him, as in one who has authority over you life, very much like a parent and child relationship. The fear is not like being terrified of a momma bear protecting her young, but of the discipline that comes from a loving parent.

The understanding a young child has that his parents know more then him and have their best interest at heart is what is represented here. And like many kids, we all think we know better as we get older, and that's how we end up with dragshow story time.