This node is for using the Vertex Map node with Octane. To use this node, you need to know how the Vertex Map works. For this, you can look at the online tutorials or Cinema 4D's help file.
In figure 1, a Vertex Map has been prepared for parts of the Torus object. When the Vertex Map is created, the Vertex Tag appears in the Object Manager. This tag was assigned to the Vertex Map node in the editor.
Figure 1: Using the Vertex Map node to alter the Gradient node.