Jehovah’s Witnesses do not teach that the meaning of the word soul is always restricted to mean the person. For certain that is the most common way the word is used in the Scriptures but the Jews also used it to denote the life of the person. Hence, if soul goes out of a person that means they died. If soul returns to a person that means they come back to life as a living soul, which was what occurred in the case where Elijah resurrected a child that had recently died.
In the 53rd chapter of Isaiah the prophet foretold that Christ would ‘pour out his soul to the very death.’ Since the Bible says the soul of the flesh is in the blood, in the case of Christ he poured out his life blood – his soul – to the very death.