Revelation after chapters 2&3 appears to be a compilation of how to tie the rest of Jeremiah, Isaiah, and Ezekiel into the New Covenant . the rest meaning . what wasn't fulfilled on the first advent of Christ . is supposed to be fulfilled on the second .
The phrase for "It is finished" showed up on a number of Roman tax receipts meaning "Paid in full" so it is most likely Jesus meant the power of sin, death, and the law was finished . so now we can live by the Spirit and by Grace . instead of by fear, compulsion, and the law written in stone, we live by the law He has written on our hearts .