Dry brining is brining without liquid. The salt in the rub allows the pores of the chicken to open and draw out liquid which then mixes with the seasonings of the rub. After a bit of time the seasoned liquid gets pulled back into the chicken. When dry brining, you need to give allow for the recommended time. Do not cook until the recommended brining time is completed or the moisture/seasoned liquid may not be reabsorbed which would create dry chicken.
This recipe is from Dry Brined Beer Can Chicken from the 2013 Southern Living book All Fired Up.