Hello, my doubt is regarding Genisis 4:13

And Cain said to the Lord " My punishment is greater than I canbear! Surely You have driven me out this day from the face of the ground; I shall be hidden from Your face; I shall be fugitive and a vagabond on the earth, and it will happen that anyone who finds me will kill me."

My doubt is: If Adam and Eve had two children, "Cain and Abel" who are these people Cain's afraid of being killed if they find him?

Your question seems to be theological, not grammatical. This site is for English grammar and we do not specialize in religious ideology. You should ask this very sensible question at a forum on Christianity and their interpretation of their religious texts. B the way, the same question has been raised regarding Cain's wife, just a few verses later.

17And Cain had relations with his wife, and she conceived and gave birth to Enoch. Then Cain built a city and named it after his son Enoch.