"Every August she goes to Germany."
Translation:Każdego sierpnia jeździ do Niemiec.
It's "każdego" because it connects with Genitive "sierpnia". It's harder to explain why it's a Genitive form for "Every August"... I'd just treat as a fixed phrase. When it means that something happens every August.
Applies to all months. Well, "każdy styczeń" (or "każdy sierpień") is not wrong, it just doesn't suit the context. For example you can say that "Każdy styczeń jest zimny". Which is grammatical, but a strange thing to say. I guess there aren't many occasions when I would use "każdy" + a name of a month.
Chyba nie tylko do miesięcy, no i "każdego dnia, środy, tygodnia, lata..."?
what is the difference between: < ona jeździ > and < ona jedzie > ? Does it both mean: she drives? she goes by car ?
She goes by some vehicle, possibly drives it (but we don't know that). The difference is that "jedzie" translates to Present Continuous and "jeździ" translates to Present Simple.
I didn't receive an answer yet to my previous question: Can you say in Polish < co sierpień> juste like < co rok > ?
During those two months you probably figured it out, but "do Niemca" would mean that she goes to one particular German guy ;) while "do Niemiec" means that she visits the country.