Translation:Actors are famous people.
can sławni mean "good" here?
no it never means good, only famous, well known.
I know this is probably answered somewhere else but, why is it "to" rather than "są"?
These are two interchangeable (in most cases) options. "to" sounds a bit like "=", while "są" is more... descriptive. But they both work. "Aktorzy to sławni ludzie" and "Aktorzy są sławnymi ludźmi".
More info here: https://www.duolingo.com/comment/16373167
Why is 'well known' unacceptable as well as 'famous'?
Why is The actors are famous people, wrong?
Some mistake made in the Incubator, that's why. Fixed now, thanks for noticing.