"ZA" is the standard two-letter country code for South Africa.

in the same code list, "SA" refers to Saudi Arabia, and Zambia is "ZM".

https://en.wikipedia.org/wiki/ISO_3166-1_alpha-2

ISO 3166-2 code for South Africa. It's from Dutch: Zuid-Afrika. It's used quite often to refer to South Africa; RSA or SA is also used.

"SA" is ambiguous. People do use to to refer to "South Australia" (the state) or also "Saudi Arabia" ISO 3166-2 country code.

ZA is not ambiguous, it has that going for it.

True, but I meant in South Africa, SA is the most used. Less so with RSA or ZAR. ZA is somewhat used but SA (I would say) dominates in conversation and in written text.

Zuid-Afrika, which means south Africa in Dutch. ZA remains the country's country code.

South Africa is a country?

Yes¹. It happens to be the southernmost country on the continent of Africa.

¹ https://en.wikipedia.org/wiki/South_Africa

There are 54 countries in Africa. South Africa has the largest economy, followed by Egypt, Algeria, Nigeria, Morocco, and Kenya.