The Greek word for wind, pneuma, is the same word as for spirit. Whether it means wind or spirit depends upon the context. The context here says that it blows and that the sound of it can be heard. This indicates that it is the wind. A regenerated person is like the wind, which can be realized, but which is beyond understanding. Regeneration is not a physical thing, but a spiritual thing, like the pneuma. It is like the wind. The wind is intangible. Although the wind is intangible, it can be realized. The Lord told Nicodemus that the regenerated spirit, like the wind, is not physical and tangible, but invisible and spiritual.
It is difficult to understand thoroughly what regeneration is because it is a matter accomplished by, with, and in the Holy Spirit. And it is difficult to define what is the Holy Spirit. The Holy Spirit is here. Can you define Him? He is present, constant, instant, prevailing, and available. Nevertheless, if you are to be born of the Spirit, some conditions must be fulfilled. The first condition is that you must repent and confess that you are a sinner. Then you need to believe in the Lord Jesus and call on His name. You should not just call with your lips, tongue, or throat, but open up from the depths of your being and say from deep within your spirit, “O Lord Jesus, I believe in You.” When you do this, the divine Spirit will enter into you immediately. When He comes into you, it is Christ coming into you. It is also the Triune God coming into you. The Holy Spirit is nothing less than Christ Himself. In fact, the Holy Spirit is nothing less than the Triune God. The Father is in the Son, and the Son today is the Spirit (2 Cor. 3:17). When the Spirit comes into you, both the Son and the Father also come into you. Thus, from the time that you are born again, the Father, the Son, and Spirit are in you. This Triune God is the divine life. The divine life is not separate from the Triune God. From the very moment you are regenerated, you have the Triune God within your spirit as your divine life. Now you have two lives: the human life in your flesh and the divine life in your spirit.