to also be (implies that as well as the earlier stated this is also the case)
to be ... or something
彼は教師でもあり、作家でもある。
He is a teacher and also a writer.
これは問題でもあり、好機でもある。
This is both a problem and an opportunity.
私は母でもあるし、会社員でもある。
I am a mother and also a company employee.