A polygon is a triangle in 3D space. A surface is a collection of polygons that share similar properties (like the texture).
What they're trying to tell you, is that contrary to what hardware manufacturers will have you believe, there is more to the equation of "smooth gameplay" than polygon count.
Surface count and fillrate play a much more important role these days. You can easilly get away with hundreds of thousands of polygons on screen at the same time, if they're really small (relative to screen resolution) and all share the same texture.
What they're trying to tell you, is that contrary to what hardware manufacturers will have you believe, there is more to the equation of "smooth gameplay" than polygon count.
Surface count and fillrate play a much more important role these days. You can easilly get away with hundreds of thousands of polygons on screen at the same time, if they're really small (relative to screen resolution) and all share the same texture.