It is the Spirit who gives life; the flesh profits nothing. The words that I speak to you are spirit, and [they] are life. John 6:63(NKJV)
In the preceding verses (John 6:48-62) Jesus told the Jews that unless they ate His flesh and drank His Blood they had no life. They took Him literally and thus we’re offended and left. This is the flesh mindset and it doesn’t profit.
But Jesus meant that what God would do through Jesus’ flesh and Blood in His suffering and death would bring life to all who believe. This is how His Words were spirit and life.
When you read or hear the Word of God and see demands you should do in your natural human strength and wisdom in order to get results, then that’s the flesh mindset. It doesn’t profit. But if you see what God has done and can do through you in His mighty strength, then the Word is spirit and life to you.