Translation:What do you still want to buy?
You are correct and I understand that it now accepts "what else do you want to buy" which is what we would more often say in English.
But it is also important to realise that 'else' is not always a synonym for 还 (hái) because it means all of these things:
still / still in progress / still more / yet / even more / in addition / fairly / passably (good) / as early as / even / also / else.
For some reason, DL or my Internet isn't letting me comment on one of the previous questions regarding size of 'pants'. NEVER talk to an English person about his or [especially] her pants! N E V E R !!!!! In English, 'pants' are the clothing worn under trousers! Avoid the embarrassment by using the English word: 'trousers'!
Some characters are pronounced differently, and therefore have a different meaning. Pinyin gives for 还 3 possibilities: hái, huán and xuán [See: www.chinese-tools.com/tools/sinograms.html?q=%E8%BF%98].
If such a character is in a sentence, you know which word is meant, but if it is separate not.
You heard "huán" when you clicked on this character separately, so apparently Duolingo has programmed 还 as "huán".