I get the impression sometimes that some things here have to do with a too strict kind of translation into or from English. E.g. the English word "beautiful" can be translated by krasny or hezky, but in this course only krasny is seen as correct, and hezky has to be translated as pretty, whereas in English a pretty girl = a beautiful girl. Same with muži, both men and the men are correct translations, but the latter is considered wrong here. So correct translations from English to Czech or vice versa are sometimes considered false, and that is a bit frustrating when they are not in reality...
ingmar, there is no demonstrative adjective (such as to, ty, etc.) in the Czech sentence, so it is better to translate it without using 'the'. This DL program is quite consistent on that point.
Here a woman ( I assume) is saying "Men don't understand us," meaning all men, not a particular group of men. So "The men don't understand us" would not be correct. (Unlike in some European languages, in English the definite article is not used when denoting all members of a class.)
There is no context suggesting that is is about men in general, instead a more specific group of men. In previous lessons I got the impression that it is ok to leave out any translation for 'the' if it is not clear that there is a very specific group to point out. In such case's I would also use 'Ti'.