"Preliminary discussions regarding Watchmen have occurred, but we have no additional information and no deals are in place."
So, it is a thing, it is a thing at HBO, but it's not a thing yet, basically.
The initial report was that Zack Snyder, who directed the Watchmen movie released in 2009, was in discussions with HBO about adapting the comic book again, this time as a series. No details have been discovered about just how that would be done, whether it's adapting the prequel series that were released by DC Comics a few years ago, or doing original stories set in that universe. If HBO's statement is to be believed, maybe they haven't figured that out just yet either.
After Snyder's Batman v Superman: Dawn of Justice is released next spring, he has the two-part Justice League epic to put together, which all of WB/DC Entertainment's other films will revolve around. So chance are, he's not going to be heavily involved in a TV series anytime soon.