From Stonekettle’s article:
Look here, as a lawyer, Kaine spent two decades representing poor people who had been discriminated against in housing and employment based on race and disability. He won landmark cases and changed the law regarding fair housing, employment, and representation for minorities - and a lot of that was pro bono.

That’s the kind of thing Sanders talks about regularly, isn’t it? Kaine didn’t just talk about it, he did it.