When I was growing up, most of the studies on the Spirit had to do with what the Spirit does not do. But there is so much in scripture that tells us what the Spirit does do. A place to start is to look at the word, "Spirit."The Old Testament Hebrew word, "ruach," means "breath, wind, spirit. As "spirit," it can refer to a person's disposition, mood, or attitude, such as in Isaiah 19:3. It can also refer to a person's mind, skill, aptitude, such as in Exodus 28:3 or Isaiah 29:24, where ruach is sometimes translated "mind." Spirit is also used of God, usually as "The Spirit of God/the LORD" or "Holy Spirit."
The New Testament Greek word, "pneuma," has a similar range of meaning. It means "blowing, breath, the immaterial part of a person's personality, a person's seat of insight, feeling, and will, or a 'spirit' as an independent being, which can either be a good spirit or evil one. Then there is also the Holy Spirit of God.
However, the Spirit of God is not an impersonal force. Jesus refers to the Spirit as a person, not an it, "…the Holy Spirit, whom the Father will send…"(Jn 14:26). In Psalm 139:7-8, David speaks of the Spirit and God interchangeably. The same is true in Acts 5:3-4, when Ananaias lied to both the Holy Spirit and God, and in 1 Cor 3:16; 3:19, which states we are a temple of both God and the Holy Spirit. In Hebrews 3:7-11, the Holy Spirit and God speak with one voice, which equates them as one. Therefore, the Holy Spirit is God as Jesus himself is also God (Jn 1:14; 8:58; Col 2:9). The traditional theological explanation is that there is one God (1 Cor 8:4), yet three "personalities" within the "Godhead," and the Holy Spirit is one of those three. This is usually called the Doctrine of the Trinity.
The use of the word "Holy Spirit" to refer to the third part of the Trinity reveals something of the nature of the Spirit. As the "breath" of God, the Spirit is an agent of life, initially given at creation (Gen 1:2; 2:7; Ps 104:29-30; Job 33:4). However, due to sin, that life was disrupted (Gen 3). The result was death, which was ultimately alienation from God.
However, God promised he would restore life, and the Spirit would have a part in this. God would pour out the Spirit, who would bring new life (Is 32:15; 44:3-4; Ezek 37:13-14).
These promises began to be fulfilled through Christ. He would give the Spirit without measure (Jn 3:34), which would be a rebirth (Jn 3:3,5), and new life (Jn 6:63; 2 Cor 3:6) for to those who believe (Jn 7:39), repent, and are baptized (Acts 2:38). The Spirit would be "poured" out generously, like "rivers" of living water (Jn 7:37-39), and remain forever (Jn 14:16), unlike the Old Testament where the Spirit often came upon someone temporarily then departed (Num 24:2; Jud 6:34; etc.). However, the Spirit would not be given to the world at large because they do not accept Christ (Jn 14:17), but only to those who faithfully obey (Acts 5:32).
So, not only was the Spirit and agent in giving life to the creation, but also in our re-birth as well.