Jehovah's Witnesses believe that the body itself is the soul. And they believe that man has no spirit. But both are wrong because the Bible teaches and distinguishes body, soul and spirit.
1 Thessalonians 5:23
Now the God of Peace Himself, and you may have kept your soul and soul blameless at the coming of Jesus.
Hebrews 4:12
For the word of God is living and active, sharper than any two-edged sword, piercing to the division of soul and spirit, of joints and of marrow, and discerning the thoughts and intentions of the heart.
And because they believe that the body itself is the soul, they claim that the person has no consciousness after his death. But as already mentioned above, the soul is not the body and the man therefore still has a consciousness because the soul is still alive. The souls of the dead are in the realm of the dead. John saw the souls of the dead and he also saw how the souls spoke to God.
Revelation 6:9
When he opened the fifth seal, I saw under the altar the souls of those who had been slain for the word of God and for the witness they had borne.
10 They cried out with a loud voice, “O Sovereign Lord, holy and true, how long before you will judge and avenge our blood on those who dwell on the earth?”
Jesus also distinguished between soul and body. Man is able to kill a man's body but not his soul. Only God can do that.
Matthew 10:28
And do not fear those who kill the body but can not kill the soul. Rather fear him who can destroy both soul and body in hell.
What is the difference between body, soul and spirit?
The body is the physical part, you can touch it and see it. The soul is your personality (will, conscience, mind, thoughts ...) you can not touch or see the soul and yet it feels pains like the body. The difference to the body is that one can not hurt the soul with blows but with insulting words. With the spirit, you can communicate with God.
We humans are therefore also a small Trinity, we consist of three but are only one human being.
God the Father is the soul, so he is the personality, from him came Jesus and the Holy Spirit. Jesus is the body and the Holy Spirit is the spirit.