"Someone should explain this sentence to us."
Translation:Někdo by nám tuto větu měl vysvětlit.
Apart from my mistranslation of "this" as "tu" instead of "tuto", why is the word order of my sentence incorrect? "Měl by někdo tu větu nám vysvetlit."
It just is not natural. When 'something' 'somebody'and such are in a sentence as an object, they typically stand at the beginning. You could start with the 'sentence'
Tu větu by nám někdo měl vysvětlit.
Czech word order is very flexible till it is not all of a sudden