Tents are items you can buy from a vendor if you build the lvl2 Tannery in your Garrison. With tents, you no longer need to be in a town/inn to gain rest state. Just throw down a tent and log out!
Additionally, tents give you a 1hr stat buff (10% all stats on the beta) if you stay inside of it for at least 10sec. It’s like a food buff.