Primitives Object, as the name implies, is exactly that - it creates primitive objects. Right now it only creates Cubical lattice of vertices and also a spherical lattice of vertices.
Primitive Type: Sets the primitive type to Cube or Sphere.
Cube: Sets the X,Y,Z num of points for each cube and also the dimensions of the cube.
Sphere: Sets the radius of the sphere and also set the number of slices, stacks and layers in the sphere.
Generate Faces: Generate Faces in the XY or XZ or YZ plane. You can render the faces using the Plexus Facet Render Object.
Transform:You can Rotate and change the center of the primitive.
Color: The default color of the vertices.
Opacity: The default opacity of the vertices.
Group: The Group which the Object belongs to in the Plexus.