'Oratory' is the art of public speaking and in Ancient Rome society it was valued highly.
Trained to be eloquent and persuasive, orators used their skills and position in society to inform and influence public opinion, sway judges and, sometime denounce political figures.
Oratory in Rome, at that time, was very much a male arena. Some elite men trained to be public orators throughout their lives.
Our public 'orator' is making a particular point while standing on a marble plinth to address a crowd of onlookers. This was a very early form of mass communication.