Eve gives birth to Seth
Adam and Eve had a son after Cain killed Abel, and named him Seth.
Key passages
Ge 4:25

Then Adam knew his wife again, and she gave birth to a son. And she called his name Seth, for she said “God has appointed to me another child in the place of Abel, because Cain killed him.”

Ge 5:3

And when Adam had lived one hundred and thirty years, he fathered a child in his likeness, according to his image. And he called his name Seth.

See also