'Offspring' in the Bible

“Teacher, Moses wrote for us that if a man’s brother dies, leaves his wife behind, and leaves no child, his brother should take the wife and produce offspring for his brother.

There were seven brothers. The first took a wife, and dying, left no offspring.

The second also took her, and he died, leaving no offspring. And the third likewise.

So the seven left no offspring. Last of all, the woman died too.