The DNC is filing a lawsuit against Trump, Russia, WikiLeaks and others for the 2016 election.
I like how they're dragging Assange into this, too. "Russia colluded with the Trump campaign in order to sabotage Hillary Clinton! And it's WikiLeaks' fault".
I mean... it literally was, in part. Far as we're aware from publicly available stuff, signs point to wikileaks working with russia and republican efforts to shit on their political opponents. They're a relatively minor player, I suppose, but if you're filing that sort of lawsuit they're fair game.
As for what's expected to be achieved, well, the article straight up says it. Monetary damages and public acknowledgement the entities in question did, in fact, conspire* to sabotage DNC efforts related to the 2016 campaign. If they've actually reached the point of physically filing a lawsuit like that, they probably think they have the evidence needed to get that, or some portion of it, out of a NY federal courtroom.
* Will say, I could half see that wording, specifically, being used as half the point. The collusion this and collusion that shite thrown around is legally bullshit, an empty thing with no legal definition worth mention.
Conspiracy, on the other hand, very much is a legal concept that exists with weight and a nasty set of teeth. If certain folks start denying they were conspiring it might take a hefty chunk out of their ass in the futute and good goddamn riddance if it does.
E: And it's worth mentioning that something similar was filed against nixon, back in the day, that ultimately resulted in a good pile of settlement money. So... shit might actually be cash, ha.