What is QA?

I think my boss give us a good opinion.  Why need we a QA test team?

The QA team does not only discover the bug from SW/HW.

More important concept, More important concept, what reason causes this issue after testing this issue. 

Then it can reduce SW/HW debugging time.

Now ,  we often hear the test link.  We only see the pass/failed item of testing.

Can we get more information for debugging from these test case?