I have checked the FAQ article yet I didn't see any subtopic that is related to the question. FAQ did not even talk about the mixing code. And I believe that op can direct me how to get that mixing bcoew so I can also use the mix to mix coins
The
mixing code is autogenerated by YoMix after you perform a mix without specifying a code, specifically used so that you don't receive your own UTXOs back as an output (which would make the mix useless).
The description is inside the tooltip on the homepage:
After first mixing you will receive the mixing code, save it and use to avoid getting your own coins from previous mixings.
So basically it's not like some kind of session ID which allows you to continue accessing your coins, it's just a data entry to prevent you from getting your coins back (split up into whole units with 1 transaction of course).