This is the 11253rd most frequent Russian word.
двойня
"Двойня" means "twins" (specifically non-identical or fraternal twins).
The word "двойня" here is used to mean a pair of twins born at the same time, indicating a general plural reference.
У моей подруги родилась двойня.
My friend had twins.
In this sentence, "двойня" is used to refer to the children together as a significant unit, emphasizing familial relations.
Я видел фотографии их двойни — такие милые дети!
I saw photos of their twins—such cute children!
Here, "двойня" represents the speaker identifying as the parent of twins, implying the bond and family relationship.