The vo'cume is a small spherical Goa'uld device that projects an enlarged recorded audio/video holographic image. It was used as a training device by the young soldiers training under the Rules of Engagement, and as a means to project an image of Apophis as a symbol of authority. SG-1 was able to adapt the device to interface with a laptop computer and to project a prerecorded image of Apophis's death in order to convince the soldiers to end the war games.
Cross Reference: Goa'uld Language, Holographic Projection, Rules of Engagement
Episode Reference: Rules of Engagement