"The days are long."
Translation:Dny jsou dlouhé.
There is, see the declination tables in the Tips and notes (perhaps only in future lessons you still do not have access to) or any other grammar handbook. The genitive case is already different dnů vs. žen (plural) and then many other cases also differ. Also note that there are multiple paradigms for each gender.
The rule number one is that Czech is an SVO language and you should deviate from this neutral order only when you have a specific reason to do so.
Perhaps we could consider "Dny dlouhé jsou" which means "The days ARE long." "They ARE long and not short as you suggested."
"Jsou dny dlouhé" is really just the word order for a question.