Robes, also known as cowls, were loose-fitting clothes with sleeves. The Jedi and Sith both often wore robes beneath a cloak, and the Jedi had their own particular style of robes. Darth Sidious wore a hooded zeyd cloth robe, while Darth Vader and the Imperial Guard wore robes with armor. Jawas wore robes with a hooded cowl.
Folding one's hands in front of them, such that they were obscured by their robes, was considered the most formal way one Jedi could address another.