I don't understand why "può" is translated as "we cannot" or "you cannot".... Why is it not "he/she cannot"? I thought perhaps it was something to do with the imperative, but my Italian Verb tables do not give an imperative for the verb potere. Any help appreciated, thanks.
This sentence shows how Italians make generalizations. In Italian you use impersonal "si" with a verb in 3. person singular or plural to make generalizations.
Check this for a better explanation: http://tutorino.ca/grammatica/2007/4/10/the-impersonal-si.html