“And I believe in the Holy Spirit, the Lord and Giver of life; who proceeds from the Father; who with the Father and the Son together is worshiped and glorified; who spoke by the prophets.”
The Holy Spirit is beyond all doubt the most mysterious member of the Trinity. Here we learn that the Holy Spirit is “the Lord and Giver of life.” That means that the Spirit is in charge of and is the Giver of eternal life.
“Who proceeds from the Father” is the original wording. The Pope added “and the Son.” The Eastern Orthodox say that only an ecumenical council can change what an ecumenical council created.
In the Episcopal Church we say “Who proceeds from the Father and the Son.” In my mind I interpret this to mean, “The Holy Spirit proceeds from the Father and [is sent by] the Son” (John 16:7).
“Who with the Father and the Son together is worshiped and glorified” means that the Holy Spirit is God. This is the foundation of the doctrine of the Holy Trinity. Each member of the Trinity is fully God, but at the same time, is distinct from one another.
“Who spoke by the prophets” indicates that the Holy Spirit is the source of Divine inspiration. God the Father works by the Son through the Holy Spirit.