The DLC is called Vallhund, and it'll let you recruit a new Norse dog companion to your camp. CCCP didn't give away any more details or say how much Vallhund would cost, but it did release two screenshots of the dog looking cute, one above, one below (the second suggests you'll be able to play fetch with it in your camp).
Alongside the paid DLC, CCCP will release a new, free game mode focused on exploration and make more minor gameplay tweaks, including giving enemies random traits. It promised more details on its devblog soon.
The next new mode will arrive in a paid expansion before the end of the year, and the third and final DLC is due next year.