tris in Rendering Statistics Window

Ok, in Rendering Statistics Window documents it's written..

Tris and Verts: The number of triangles and vertices drawn.

I want to know it shows the number of traingles drawn or the no. of traingles drawn request send by cpu to gpu? For testing i take a long 5000 m road having around 5000 tris, now in rendering statistics window it shows 5000 tris and 1 draw call. but if i change the frustum the no. of tris never change. why? the number of tris drawn should be depend upon the frustum. NO?

if it doesn't depend upon the frustum value then is it better to divide that object to small parts? so that the no. of tris decrease and object draw according to the frustum?