What does Genesis 4:2 mean?

After Cain's birth, Adam and Eve conceive again. Abel, Cain's brother, is born. The story jumps forward in time in this verse, leaving quite a few details unanswered. This is normal for the book of Genesis, which often describes major portions of history in just a few summary verses.

Among the unanswered questions of this particular verse is whether or not Adam and Eve had additional children in the meantime. Ancient genealogies often only mention the "important" offspring, so to speak. So, it's likely, but not certain, that Cain and Abel had other siblings prior to their conflict. A major point in favor of this view is Cain's fear of other people in Genesis 4:14, and the mention of his wife in Genesis 4:17. These imply that there were other people alive at the time of his conflict with Abel, meaning other children of Adam and Eve.

That being said, nothing in the text, or the story, requires that there were other siblings, nor does it demand that there were not. This is simply an open point on which Scripture does not provide clear details.

This verse reveals the brothers' professions. Abel keeps sheep. Cain farms, working the ground for crops. Both were respectable and necessary professions among the second generation of pioneering humans.