These blessings all come in Christ. God blesses us “in Christ”. God has chosen to extend his blessings to the world through Christ. Only those who are united with Christ receive them.
These are spiritual blessings. Paul says God “blesses us with every spiritual blessing in the heavenly places. I think what he means by “spiritual blessings” are in contrast to “material blessings”. This new kingdom is spiritual.
These spiritual blessings are in contrast to many of the promise of material blessings in the Old Testament. For example, look at Deuteronomy 28:11. If Old Testament Israel obeyed God and kept his covenant, he would make their crops and livestock increase. God does not promise the church its members’ salaries will increase or their cars will multiply. That is why prosperity preachers tend to quote Old Testament promises to Israel to say believers will receive wealth and health if they believe and give.
These blessings come in the “heavenly places” according to the ESV, or the “heavenly realms” in the NIV. I take this to again mean the spiritual realm. This phrase appears 5 times in Ephesians. Christ ascended to the heavenly realm. Later on, in verse 20, Paul speaks of Christ raised from the dead and seated at the right hand of the Father in the heavenly places. Psalm 110:1 starts it off with a prophecy that the Lord would do this. Jesus, in Matthew 22:44, applied Psalm 110 to himself. Several other New Testament verses speak of this.
In Ephesians 2:6, Paul said God raised us up with Christ and seated us in the heavenly places in Christ. So, even though we live here in this physical realm in our mortal bodies, in Christ we enter into spiritual life and blessings of God.