The idea of redemption and of Yahveh as Israel's redeemer (go'el) derives from the obligation in ancient customary law to buy back the freedom of a kinsman in indentured service, usually as a result of unpaid debts. The practice provided a ready analogy for the belief that Yahveh had, so to speak, bailed Israel out of Egypt, though the party to whom the payment was made remains unclear. (The problem persisted in the Christian appropriation of this language in the doctrine of redemption by satisfaction: paying a price, but to whom?).
Here we find the curious idea that Israel will be redeemed once again not by monetary payment (cf. 52:3) but by handing over, presumably to Cyrus, Egypt, Ethiopia (Sudan), and Seba (probably in the Horn of Africa) ... .
How do verses 3-4 foreshadow what God eventually does for his people?
Look at verses 5-7. What would it be like to have God act on your behalf in this way?
If you knew nothing about God except what you learned from this passage, what would you find him to be like?