This is the 10656th most frequent German word.
rettern
"Rettern" is not a standard German word. Perhaps you meant "retten," which means "to save" or "to rescue."
In this sentence, 'retten' is used to describe saving or rescuing someone (the bird) from a harmful or difficult situation.
Ich habe den Vogel aus dem Netz gerettet.
I rescued the bird from the net.
Here, 'retten' again implies the act of saving, emphasizing the urgency and danger involved in the situation.
Die Feuerwehr rettete die Familie aus dem brennenden Gebäude.
The firefighters saved the family from the burning building.
In this instance, 'retten' is used figuratively to mean preserving or protecting something valuable from decline or destruction.