Genesis 4:11-15 meaning

God has already cursed the serpent (3:14), childbearing (3:16) and the ground (3:17), now He curses Cain. Because of Abel's blood defiling the ground, God pronounced that the ground would not produce anything for Cain. Cain would never get fruit from a harvest or be a farmer ever again.

Cain complained that the punishment God gave him was more than he could take. He was also worried that he would be in danger from those wanting to avenge Abel's death. So, through grace, God put a mark or sign on Cain to protect him from being murdered. The sign was not a sign of God's curse on Cain, but in order to provide Cain safety and protection. It's unclear what exactly the sign was. One thing is sure, it was a seal from God with a promise that if someone killed Cain their vengeance would be seven-times worse.

He became a fugitive and a vagabond, literally having to keep moving and wandering in the land. All the while, Cain still did not repent of his sin. He was concerned only with his punishment, not his relationship with God. If Cain had remorse for killing his brother, it is not recorded. It is noteworthy that Cain's punishment is a form of exile, similar to Adam and Eve's consequence for their sin when they were exiled from Eden. Cain was exiled from farming the land. Capital punishment is not introduced to humanity until the Noahic Covenant in Genesis 9.