Given that Michael Bay is still directing Transformers movies, there's a good chance you already know how batshit this trailer will be before you finish reading the sentence.
The basic idea is that Optimus Prime and Marky Mark are making tracks to Cybertron. It's supposedly a soft reboot of the franchise, with The Last Knight exploring two different timelines and just how the Transformers ended up splitting into factions.
I'm still waiting for the Transformers movies to regain the charm and cheek that the original film in 2007 had. I'm not getting my hopes up, but we'll see on June 27 next year whether Bay has managed to make the films a little more likeable.