John 16:8

And when he comes, he will convict the world concerning sin and righteousness and judgment. (John 16:8)

Three points:

1. He

The Holy Spirit knows everything, is all powerful, and is everywhere. The coming refers to Pentecost.

2. Convict

Convict has the idea of confronting someone and showing that they are wrong. It is used 17 times in the New Testament as in "Moreover if your brother sins against you, go and tell him his fault between you and him alone. If he hears you, you have gained your brother. (Matthew 18:15) and Then those who heard it, being convicted by their conscience, went out one by one, beginning with the oldest even to the last. And Jesus was left alone, and the woman standing in the midst. (John 8:9)

3. The World

This is not a select group of people; it is all of us.
...for all have sinned and fall short of the glory of God(Romans 3:23)