In Sacred Scripture, the Holy Spirit is called with different names: gift, Lord, Spirit of God, Spirit of Truth and Paraclete, among others. Each of these words indicates something of the Third Person of the Holy Trinity. It is a "gift", because the Father and the Son send it to us free of charge: the Spirit has come to dwell in our hearts. In Him we have access to the Father by the Son.
The Spirit is "Lord" and "Spirit of God", which in Sacred Scripture are names that are attributed only to God, because he is God with the Father and the Son.
It is "Spirit of Truth" because he teaches us in a complete way all that Christ has revealed to us, and guides and keeps the Church in truth (cf. Jn 15:26; 16:13-14).
It is the "Paraclete" (Comforter, Advocate) promised by Christ, who is the first Paraclete
At our Profession of Faith/Creed we pray some of the biblical expressions with which the Spirit was named. By saying that he is a "giver of life", it is in reference to the gift of divine life given to humanity. As Lord and giver of life, he is God with the Father and the Son and therefore receives the same worship as the other two divine Persons.
The last part of the creed also mentions the mission that the Spirit performs among men: "He spoke through the prophets." Prophets are those who spoke in the name of God moved by the Spirit to move to conversion to his people.
We believe in the Holy Spirit, and this same Spirit continues to act in each of us.