The Ba’al Shem Tov explains that this pasuk harks back to God’s command to create the heavens and is to be understood literally. God’s command, “Let there be a firmament …,” (Breishis 1:6) the very words of the declaration, stand firm in the heavens and give them existence. The same applies to all the commands of the Creation.
Why is this so and what is its significance? The Sfas Emes explains that God's creation commands (i.e. "Let there be light", etc.) are at the root of every part of the Creation. The spiritual sustenance that enables every part of the Creation to continue to exist flows out of God’s very declarations that brought them into existence in the first place. The spiritual energy at the source and its physical counterparts are therefore intimately connected. The Creation was structured so that the spiritual energy actually becomes the physical creations.
Chazal quote this pasuk relating it to Rosh HaShanah because Rosh HaShanah represents the spiritual energy before it changes into distinct and disparate material creations. The teki’ah sound of the shofar alludes to this concept. The teki’ah is a simple sound. It represents sound before it is broken into parts by speech and reminds us of the source of life and existence before it becomes physical and broken into disparate physical forms.
On Rosh HaShanah we want to connect – to experience – through the sound of the shofar, to God’s spiritual life force. May we merit it!