These are great questions. I suppose we might find ourselves discussing like a Jewish family, arguing about anything and everything.
I say "argue" because there is much that could have different meanings, imagery, analogies et al but this is what I found:
Ezekiel 36: 25 Then will I sprinkle clean water upon you, and ye shall be clean: from all your filthiness, and from all your idols, will I cleanse you. 26 A new heart also will I give you, and a new spirit will I put within you: and I will take away the stony heart out of your flesh, and I will give you an heart of flesh. 27 And I will put my spirit within you, and cause you to walk in my statutes, and ye shall keep my judgments, and do them.
We stand on that it is the breath of God gives life. The very Spirit of God.
As I view it, to have a new heart and a new spirit denotes a spiritual birth, a new beginning a new life. Interestingly enough, it also mentions the water that cleans.
The flesh is circumcised (that which is flesh is flesh) - but it is the spiritual heart that is circumcised by God (that which is spirit is spirit)
Deuteronomy 30:6 And the Lord thy God will circumcise thine heart, and the heart of thy seed, to love the Lord thy God with all thine heart, and with all thy soul, that thou mayest live.
I view it as becoming part of the Kingdom of God. I am a citizen of the US because I was born in the US. If you were born in Eswatini, you are in its Kingdom. So when one is born by the Spirit of God, having received a new heart and a new spirit, you have entered into God's Kingdom where He is now the King of your life.
That's my two cents.