If anyone has this kind of question, it’s best to consult not just the various translations, but also a good Hebrew word-for-word translation. (You will often see this kind of thing called an “interlinear” translation.) Biblehub is a Protestant site, but it does have this available for the Hebrew text of OT books and the Greek text of NT books that are in the Protestant version of the canon. You can find other versions elsewhere. It’s also helpful to check out the Septuagint Greek reading of OT Hebrew passages, if you see something looking weird.
The Hebrew version of this passage says “Your iniquity is pardoned/paid off and your warfare is accomplished/served out.” In this context, “warfare” seems to mean either Israel’s spiritual struggle to stay Jewish and monotheist in Babylon, or the general war-related bad stuff that happened to Israel, like losing the war and getting dragged off into exile. But it can also mean a time of service or duty, like serving in the army.
The word itself is “tsaba,” which literally means “host, army.” (You probably remember a derivative of it from the expression “Lord God Sabaoth,” Lord God of Hosts.) It can also mean a term of army service or warfare (ie, army stuff). Numbers 4:28 applies it to the Levites’ term of service. The same kind of figurative use is in Job 7:1 and Job 14:14.
The Septuagint Greek replaces “warfare” with “humiliation” and switches up the order of the poetry: “her humiliation tapeinosis] is accomplished and her sin is untied.”
