Answer: The human “soul”—our English translation of the Hebrew nephesh—is our living, breathing, physical existence. Some may be surprised to learn that this soul is not immortal—it can die. In the New Testament, Jesus warned that souls can die (Matthew 10:28), and we find this same teaching in the Old Testament as well: “The soul who sins shall die” (Ezekiel 18:20).
Yes, the human soul is mortal unless it receives from God the gift of eternal life. Yet there is something more that distinguishes human soul from animal soul. We read that “there is a spirit in man, and the breath of the Almighty gives him understanding” (Job 32:8). Also: “For what man knows the things of a man except the spirit of the man which is in him?" (1 Corinthians 2:11).
Unlike all the other animal species, God has made human beings in His image (Genesis 1:27). We have been given a human spirit that animates our soul with mind-power far beyond what animals can muster. Upon death, the human consciousness ceases (Ecclesiastes 9:10), the human spirit returns to God who gave it (Ecclesiastes 12:7), and we (unconsciously) await the resurrection (John 11:25). For more about death and the resurrection, read.
Yet even this spirit in man does not give us immortality. Only if we receive the gift of immortal life (Romans 6:23), will we be resurrected as spirit at Christ’s return, after our nephesh has died.