Translation:My aunt can speak both Chinese and English.
Interesting that Google gives "sia ... sia" but also translates "sia ... che" correctly. So I tried experimenting. It seems a string of "sia ... sia ... sia ... sia" is possible, or perhaps ending with a "che" e.g. "Parla sia ... sia ... sia ... che" = "She speaks ... and ... and ... as well as ..." Unfortunately google still starts with the word "both" even though there are more than two. Can an Italian please confirm that such a string is possible?
I wrote "My aunt knows both Chinese and English" which I would argue is a more accurate translation, although it does omit "to speak". Would "knows how to speak" have been marked as correct? I'm still not sure how to use 'sapere' and 'conoscere' in Italian - obviously knowing how to speak and being able to speak are more or less the same, but if they've given the verb "sa" surely it should be "knows" in the translation?
It's a wrong english translation a more accurate would be: "My aunt is able to speak chinese as well as english." - Of course to refer to "chinese" as a language is as wrong as to say that in Mexico people speak mexican, or that in America they speak american. - the proper sentence should say "mandarin" as that is the official langauge in China.
you don't have to use the article with a family member in singular
It's closer to 'knows how to speak' since it's from sapere. Can is idiomatically fairly close to that, but 'is able' is just less common enough that it is linked with potere and thus not close enough for this. Since one of the things they are hoping you learn is what 'sa' (from sapere) is.
sometimes the english answers in duo lingo are debatable ( i am native) .. there is no difference in this (unspecific) context. we (english) just don't SAY: 'is able'. maybe in a more formal (written?) context such as for example a job application. but it is not wrong. p.s. i am disappointed not to find the greek for english speakers course available. are you greek? maybe you could give it a push!