Depending on the roughness or smoothness of the surface, it will increase friction if it is rough,(which has more microscopic hills and valleys). If the surface is made of a smooth material, it will decrease friction
Friction is resistance to motion along the concerned surfaces.The more the surfaces are uneven that is, they are having bumps and depressions, the more is their tendency to resist the motion.And...
Surface does NOT affect force of friction. Ff = N*u u being coefficient of friction and N being normal force. No wheres in the equation is surface area is used thus force of friction is NOT affected...