The word 'person' is tricky when dealing with that which is Spirit, but there is a sense in which the Holy Spirit has attributes of personality that can also be seen with God the Father, and with Jesus, the Son, and we don't have problems seeing how they are two distinct persons. All the scriptures in the Bible about the Holy Spirit need to be collated to form a whole picture. But here are a few...
The Spirit of God moved over the dark waters of our newly created Earth, doing His work of bringing order out of chaos, light out of darkness - Genesis 1:2.
He creates us - Job 33:4.
The Holy Spirit anoints God's people and guides them; all Christians are anointed - Psalm 139:7, Rom 8:1-17
To be without the Holy Spirit is a dreadful thing - 1 Samuel 16:14, Psalm 51:11
The Holy Spirit inspired the writing of all of the Bible and gives the understanding of it - Jn 15:26, 2 Pet 1:20
Jesus said that after He returned to Heaven, He would send the Holy Spirit to Earth to indwell believers - Jn 16:7.
The only unforgivable sin is to blaspheme against the Holy Spirit - Mark 3:29
You can only blaspheme against a person (not a commodity, like electricity!) See the link.
There is so much more. If I made a list of everything the Bible says about the Holy Spirit it would run to pages. However, those who talk about the Holy Spirit as 'it' don't really know who He is! He is the third person in the Godhead - uncreated, co-equal with the Father and the Son.