Well, in the grammar lessons it says:
(Questioning 'To':) ''Czech doesn't have articles. Mladá dívka could be young girl, a young girl, or the young girl, depending on context.''
So if I say 'zvíře je mladé, ale velké', it is right too?
That would work in Russian, but not in Czech. Here you really do need the pronoun to signify it is THE animal. It is not always necessary, that's why the notes says what it says but most often it will be there.