Visual SLAM describes the simultaneous localization and mapping. This is the same process as with "normal" SLAM. A sensor is localized (tracked) and a map is built at the same time.
In Visual SLAM, cameras are primarily used. These are monocular, stereo and RGB cameras. In addition, there are other sensor systems which are used, e.g. visual inertial systems. Visual SLAM only works well in areas where there are sufficient visual differences.
