Translation:It is colder in winter than in summer.
Yes "Quand" and "Qu'en" sound the same.
BUT, if you pay attention the voice says "nété" and not "été" at the end of the sentence. So it's necessarily "qu'en" because like this one ends with a "n" you have to make a liaison and say "n-été". If "quand" was there (what is impossible because it doesn't mean anything in this case) the lisaison would not be the same ;)
Im sick of this new duolingo. You can never understand what is being said as the fast is ridiculous for a non native speaker and the slow always sounds like grunts. I used to be able to not have the type what you hear. I dont give a gd about writing. I want to speak period. Give that option back.