At the root of Yirah, it means to “see” Hashem. When you come to “see” Hashem you will be both in awe and in fear.
Not the fear of a gang of youths following you, but the fear of the King who you will be called before to have your service to him evaluated, as his executioners stand beside him with their axes, and you see all this.
When one knows he will be judged in righteousness, he will be afraid.