The term z(u,v) represents a function used in the parametric representation of surfaces, where 'u' and 'v' are parameters that define points on a surface in three-dimensional space. This notation allows us to express surfaces as a collection of points that can be traced out by varying the parameters 'u' and 'v', thus providing a clear way to visualize and analyze geometric shapes in calculus. The use of z(u,v) is essential for connecting the surface's height at any given point (the z-coordinate) to its corresponding (u,v) pair.