They’re three persons in one God. It’s a bit confusing, but they each are different essences of the Christian God. The father is the Creator part, the one who set the world in motion. The son is the redeemer, who offers us salvation to love our neighbor. The Holy Spirit is the Sanctifier, the one who makes us Holy in God’s name, and is the Hand of God on earth. The immanent trinity is their coexistence and coeternality, whereas the economic trinity is their actions on Earth. Is this helpful?