This is one of the many prophetic verses in the Bible. It was written hundreds of years before Christ. It explains how Christ suffered for our sins. How could an Old Testament person understand the idea of Christ dying for our sins? God was pulling aside the curtain of time to let the people of Isaiah's day look ahead to the suffering of the future Messiah and the resulting forgiveness available to all mankind. This prophesy is astounding! All you have to do is believe in Him and you will be saved.
"But He was pierced through for our transgressions,
He was crushed for our iniquities;
The chastening for our well-being fell upon Him,
And by His scourging we are healed."