Using "Single Skinned Mesh Renderer"

I’m trying to understand what the following means from a technical perspective. In the following documentation below, I’m getting a little confused with what is being suggested.

Modeling Characters for Optimal Performance

Source: Unity - Manual: Creating models for optimal performance

So, if I have a model, which has materials added to it, how do I know the number of “Skin Mesh Renderers” it actually has?

From what I understand Unity adds a Skinned Mesh Renderer to any model that is imported in from Apps like Blender or Maya. How do I insure I only have 1 Skinned Mesh Renderer?

Thank you,
Calixto

Make sure that you have only one rig/armature or however it is named in all those applications.