It's a meaning like "what else can be done?" and the implicit meaning behind it is that the thing I am doing now is the only option (at least this is how the speaker thinks)
A: Why are you putting guitar on the bed?!
B: 还能怎么样? There's no place to put it! You took all the space in the room!
Hope this helps :)
what else can I do?
What else you want me to do?