'Os meninos ouvem' could be translated by 'the boys listen' and now 'ela ouve' cannot be translated by 'she listens'? Quite strange...
Why is "she Listens" not correct?
Because "she listens" means "ela escuta".
I checked several dictionaries, and they almost all included listen as a translation for ouvir, and vice versa.
I suppose listening and hearing would be two different verbs just like in english.
Yes. Ouvir = to hear; escutar = to listen
One is active (to listen), while the other is passive (to hear).