Meaning of the paragraph

[deivaprasad]

Kindly help to understand what is the meaing of this paragraph:

"Hear that? It's the sound that shakes the skies just seconds before they're illuminated by a bright light. That's what's going on inside you -- and if you deny it, you'll only be postponing the inevitable. Why bother? Take cover, and prepare for the next rumble."

[J&K Tutoring]

It's impossible to know without further context. I can imagine a woman about to give birth, soldiers on a battlefield, or some other high-stress situation where someone who has lived through this kind of situation before is trying to calm someone who hasn't.