"In Roman times, this certificate was a list of crimes committed against the state that required "payment," much like an indictment in our legal system today. The Romans gave Jesus a certificate of debt when He was sentenced to die; it was nailed to the cross: 'Jesus the Nazarene, the King of the Jews' (John 19:19). When the crimes were paid for, the certificate was canceled and was stamped with the word tetelestai, meaning 'paid in full.'
Paul says that Jesus 'canceled out' (paid) our certificate of debt (Col. 2 v14).
Jesus' last words, His victory cry on the cross was, 'It is finished!', literally in Greek was "tetelestai!" "He said, 'It is finished!' And He bowed His head and gave up His spirit.' (John 19:30). 'Paid in full.' What was finished? His work of redemption paying for our certificates of debt against God."