Sūrah al-Qadr (The Decree) is probably most famous for describing the immense reward associated with worshiping on Laylatul Qadr (The Night of Decree) in the last ten nights of Ramadan, the month of ritual fasting.

It appears that the contents of the sūrah form a parallel structure.
[A]/[A’] The sūrah begins by describing the sending down (anzalnā) of the revelation on the Night of Decree during the lifetime of the Messenger ﷺ. Similarly, the center of the sūrah relates the yearly descension (tanazzalu) of the angels on that same night.

[B]/[B’] Both topics are gated by Allah’s permission and knowledge. The only thing that would allow us to know about the Night of Decree is Allah allowing us to be informed about it. In the same way, the decree (‘amr) of Allah is only known to Him and sent down by His permission.

[C]/[C’] Finally, both halves conclude with a couple of the virtues of this great night. It is better than a thousand months, it is a night without faults, and it lasts until the emergence of dawn.

And Allah knows best - والله أعلم