One of the 613 commandments of the Torah is to fear God. Although it sounds simple, it is one of the most misinterpreted commandments in the Torah. The reason for this is that Western history is tainted by social and political maneuvering involving "God's punishment," so that if a king failed to comply with a particular commandment, he was excommunicated, which harmed trade, foreign relations, and so on.
However, in Judaism the vision is that of a merciful God, "Avinu shebashamáim"—our Father in Heaven. Just as a father is merciful and kind to his child, God is merciful and kind to His children—humanity in general, and the Jewish people in particular.
Therefore, the fear of God is not the fear of punishment, since that does not mean fearing God, but rather "the whip." So, what is the fear of God?
One of the ideas that can lead to fear of God is meditating and thinking about His greatness, how He creates all the creatures of the universe, from the most insignificant amoeba through the human being and reaching the most complex galactic system, everything is created and recreated constantly by God.
This thought leads a person to position themselves correctly before God: we are insignificant compared to His greatness. One can even feel ashamed to be "in the presence" of the King of all Kings, the Holy One, blessed be He.
This is a level of fear of God.