Razvan, you have stumbled across a verse that is key to understanding a theme throughout the Gospel of John. Throughout John’s Gospel is an ambiguity between the physical and spiritual, the earthly and heavenly, darkness and light. This ambiguity makes translating this Gospel difficult. The good translation:
The wind blows where it wishes, and you hear its sound, but you do not know where it comes from or where it goes. So it is with everyone who is born of the Spirit. (John 3:8, ESV)
can also be translated:
The Spirit breaths where he/it wishes, and you hear his/its voice, but you do not know where he/it comes from or where he/it goes. So it is with everyone who is born of the Spirit.
The ambiguity of spirit/breath/wind is common in first-century languages and before. Wishes hints at the duel meaning because the wind doesn’t have a will. Note that φωνή (sound/voice) means voice in John 1:23; 3:29; 5:25,28; John 10:3-5,16,27; 11:43; 12:28,30; 18:37. Only here in this Gospel does it have the meaning sound. We hear the Spirit not as a physical audible voice but with our spiritual ears. While modern meteorology may dispute Jesus’ description of the wind, his objective was describing the Spirit and discussed how we experience the wind without seeing it rather than giving scientific detail. It doesn’t mean we don’t know the Spirit comes from God, although we are to test the spirits (1 John 4:1–3). It means the Holy Spirit is invisible but speaks to our spirit.
Note the dual meanings with σκοτίᾳ/φῶς (darkness/light, John 1:5; 3:19-21; 7:12) κατέλαβεν (overcome/understand = grasp, 1:5); ἄνωθεν (again/above, 3:3), ὕδωρ ζῶν (living/running water 4:10; 7:38); πηγή (well/spring, 4:14); βρῶσιν (food that perishes vs. endures 4:31; 6:27); ἐλευθερώσει/δοῦλός (free/slaves, 8:31-38). This can keep going on.
Note:
It is the Spirit who gives life; the flesh is no help at all. The words that I have spoken to you are spirit and life. 64 But there are some of you who do not believe. (John 6:63-64, ESV)