Death is frequently used in a figurative way in the Bible, representing a spiritual death.
This gives the translator a dilemma, because we all know that verses are taken out of context and misapplied. This happens a lot with texts describing death caused by sin. Now, while unrepentant sinners are indeed described as suffering literal death, other places are clearly describing a figurative spiritual death.
For example, Romans 6:8 says:
if we believe that we’ve already ‘died’ with the Anointed One, then we’ll be alive with him also.
Also, Romans 7:4 says:
You’ve been ‘raised from the dead’ so that you can now produce fruitage for God!
Yet this is often obscured when people take a verse out of context.
So, to prevent this from happening, in some places we put words like death, die, or dead in ‘single quotes’ to show that it’s not literal. We also insert words like spiritual beforehand where the context demands it. Did we always get it right? We hope so, but perhaps not!