...Just trying to refresh my own memory here... I think the explanarion given in the now-long-ago 'You Can Live Forever in Paradise on Earth" study book was that the "soul" was the Person, the living combination of the physical body and the spirit, or "life force" that Jehovah placed within it.
Scriptures used being Ezekiel 18:4 (The soul that is sinning will die...) and Ecclesistes 12:7 (...the dust returns to the earth...the spirit returns to the true God who gave it.) At death the body ceases functioning and eventually decays, and the 'spirit' /'life force returns to God, who gave it, and who can re-create the body and restore the spirit, of those in his memory, bringing back that unique individual Person.Thus the original body can be killed, but the soul/Person cannot be destroyed, as Jehovah always has the power to bring him back if he so chooses
They used to go into explanations of the Hebrew "nephesh" and Greek "Psyche" but that has long since been dropped, and since the 2013 revision of the New World Translatiion, the world Soul is very rarely used in Watchtower writing, although Matthew 10:28 still reads "...cannot destroy the soul..." with a footnote stating "or life, that is life prospects
I am not maintaining that this is a correct interperetation, just trying to recall what I was taught...