It means that if you arent doing anything when you can see that people are being unfairly treated then you might as well be on the oppressors side because you aren't helping, it's important to speak up to raise awareness for the unjust and to let others know that you are there for them, silence means complicity because again you are not making an effort to help others when you know that what's happening to them is wrong. if you're silent about important events then that implies you don't really care about the oppressed. example, if you saw somebody being bullied and didn't do anything about it when you could've then you'd be labeled a bystander who doesn't couldn't care less about the victim, however if you spoke up you could help to stop the situation and the bully would get punished and probably stop doing it again
