That is a reference to physical death.
Nothing to do with the state of the dead in the afterlife.
There is no “afterlife” mentioned in the Bible......nor are the words “immortal soul” found in a single passage of Scripture......by assuming what is taught in all false religion, you perpetuate the devil’s first lie....
The Scriptures teach that death is the end of life, not a continuation of it.
Unless you understand what the Bible has always taught about death and resurrection, rather than the many adoptions that Christendom took from false worship, you will continue to stumble over this belief.
There are 29 references to the "realm of the dead" in the NIV translation.
Two of them are in Acts chapter 2 and one is in Ecclesiastes 9:10
www.biblegateway.com
The NIV is not the most accurate translation, and it is always helpful to use a resource that allows you to see how other translations render a passage or verse in context.
Let me quote the first one on that list....
Revelation 20:13
“The sea gave up the dead that were in it, and death and Hades gave up the dead that were in them, and each person was judged according to what they had done.”
Where are the dead in that verse? There is the “sea” where we know some are “buried”...not in the ground, but in the ocean. Naval vessels buried many at sea because they had to. But it is not a permanent “grave” if the sea yields up her dead.
What about those in “hades”? Sheol is translated as “hades” in Greek, and this word in Hebrew is often translated into English as “the grave”.....not the individual grave of any one person, but the common grave of all mankind...the “abode” or “realm of the dead”.
What is this “realm”? It is a place where all humans go when they stop breathing. It is defined as....
“the region, sphere, or domain within which anything occurs, prevails, or dominates”. (Dictionary.com)
Adam was told that “he” would die and that “he” would “return to the dust” from which he was created.
In ancient times the dead were buried, or if they were wealthy, they had a tomb carved out of the rock as their final resting place. So “in the heart of the earth” meant being buried in the ground, or in a place carved out of the earth....a place of concealment.
Where was Lazarus before Jesus resurrected him? What did his sister say that she believed about her brother’s future. Read the whole account and see that there was no “immortal soul” ever mentioned ......Lazarus was said by Jesus to be “sleeping” in his tomb. (John 11:1-44)
He came out of his tomb, still wrapped in his grave clothes. He said nothing about being alive somewhere else.....because he was mortal and had died.....Jesus gave him back his life....he did not pluck him from the spiritual realm or paradise or anywhere else, to bring him back to this life, only to die again later from some other cause. He was still very much a mortal soul, still subject to death.
You can take apart every other mention of “Sheol” in the Hebrew Scriptures and come to the same conclusion. Jews did not believe in an afterlife.....only in resurrection, which they believed would take place under Messiah’s future Kingdom....the dead are not alive....no matter how much we wish they were.