"English actresses are pretty."
Translation:Az angol színésznők szépek.
The translation should be correct with and without "the" as well.
An article is always needed in front of the subject if the predicate is a noun or an adjective. "Angol színésznők szépek" is not correct. But once the article is there, without context you can't tell anymore if the sentence refers to English actresses in general or a specific group of them, so both translations are correct.