There are certain patterns to usage of conjunctions, and this isn't the one where you would want to use «але».
Structures like "I am doing A and you are doing B" or "it is A, not B" routinely use "а".
Yeah, this can be tricky for English speakers to sort out. If there isn't already a unit on conjunctions, it would be a cool addition.
bar_an my problem is similar if it says "а", which means and, why is the answer but?
There is rarely exact 1-to-1 mapping between languages. All languages have irregular forms which may confound us: idiomatic phrases are a particular example. When we translate, we have to use a little experience to try to understand the meaning of the words and phrases.
For example, between Ukrainian and English we are 'told' there are four words which mean 'and', i.e. та, і, а, й. However, this meaning is not exact. There are both informal usage and formal rules for which one to use when joining clauses and sentences with them.
So, 'а' can be variously translated as 'and', 'but', or 'whereas'. In the above example, 'but' seems to be the more appropriate translation.
It is worth bearing in mind that words in one language have a correspondence to words in another language. Ukrainian and English differ in many ways grammatically, e.g. cases and articles for a start, so translation is always tricky. You have to interpret as well.