From the article:

"We really are developing what I would consider a new class of vehicle," Kraus said. "We do something that's a little bit wild, which is we actually put a motor in the vehicle. So even though it's towed, it's also self-propelling. It's supporting its own drag and its own mass."

Yeah, this stumped me too. FWIW, their website is garbage. But digging around a bit, I'd say this is a travel trailer, not an RV. It does have it's own motor however, and it helps push when you're going uphill. So in theory, you could tow a larger trailer with a smaller vehicle. Or perhaps this would help if you were towing with an EV and needed the additional range?

https://www.lightshiprv.com/technology