Weldon also has a more violent head bob, where he also slaps the ground with his foot. I'm pretty sure this is just an exaggerated "HOO HAA HEAR ME ROAR" kind of thing. Lizards have poor hearing, and so mostly rely on their very good eyesight to communicate through visual gestures like this. They can recognize gestures from surprising distance! (Also people and food).
Waldo will occasionally arm wave. This is where she flexes her little arms in a graceful circle. It usually means she is showing submission. I have seen little dragons arm wave and then leap forward to nip one of their clutch mates - what subterfuge! Weldon has also employed this trick when his arch rival (another male bearded dragon) visited us. He would arm wave and then slowly come in for the attack (which we never let him do).
Beardies are great pets! They are interactive, which was surprising for me as a first-time lizard keeper, and they are also very cuddly when they want to be. Please please research before buying one though: there requirements are simple but strict. A great place to start is https://www.beardeddragon.org/articles/caresheet/. There are lots of of useful articles here!