Breakdown of Was machst du im Herbst?
du
you (informal singular)
machen
to make, to do
was
what
im
in the (used with months) / in the (contraction of in + dem)
Questions & Answers about Was machst du im Herbst?
Why is it im Herbst and not just in Herbst?
In English, we say "in autumn", but German requires the definite article for seasons. Seasons are masculine and take the dative case here, so we use in + dem, which shrinks down to the contraction im. It literally translates to "in the autumn".
Why is machst translated as "are doing" instead of just "do"?
German doesn't have a direct equivalent to the English "-ing" tense (present continuous). The present tense verb machst covers both "do" and "are doing". You just rely on the context to know which one makes sense!
If I use American English, can I translate "fall" directly and say im Fall?
No, Herbst is the only word used for the season of autumn or fall. The German word Fall does exist, but it means a "case" (like a situation) or a physical drop, never the season.