I don't remember ever seeing the word 'può' before. I assumed it had to do with 'being able to', as it reminded me of the verb pouvoir in French. However, the o ending made it seem like first person singular, which it is obviously not, and the accent on the 'ò' made that seem less likely. Is 'può' more like 'it is possible'?
"Può" is the third-person singular form of potere, the verb meaning "to be able," which you've probably seen as posso, possiamo, etc. But, some of the forms are irregular and look pretty funny. Può just happens to end in an o instead of an e or a. (Why? I have no idea.) The rest of its forms, at least in present tense, look fairly normal. The full conjugation is: posso, puoi, può, possiamo, potete, possono.
So, può = he, she, or it is able.
BTW, I think you can usually mouse over verbs to see all of the forms.
No, they mean two different things.
"He says that he can" = He informs me that he is able to do the thing.
- Can he do the job?
- Well, he says that he can.
"He says what he can" = He says what he is able to say on the subject; there are things he cannot say on the subject.
- We need more information!
- He says what he can. Maybe we should ask someone else.
Actually we have, DL may not have actually gone over all of the conjugations in the lessons but they have used some of them.
For "dire" the conjugations are: io dico tu dici lui/lei/Lei dice noi diciamo voi dite loro dicono
For "potare" the conjugations are: io posso tu puoi lui/lei/Lei può noi possiamo voi potete loro possono
"Lei" can be "she" or the formal "you", which could be why it accepted "you", but the "io" form is "posso". Strange.
It's useful to stop thinking of translating as "word A = word B" and start thinking in terms of how the word is used in the other language. English also has plenty of words that have different meanings or connotations depending on how they're used. But different languages don't line up with each other like that (it's part of what makes them different). And the less concrete meaning a word has, the more likely it is to have a different range of meanings and uses in different languages.
Imagine an Italian speaker trying to deal with "like":
I like books like that.
The first "like" is the verb "enjoy" and the second "like" is the preposition "similar to".