ESD stands for electrostatic discharge, which is a common occurrence for surfaces experiencing heavy footfall. Static charge builds up on the floor due to friction or usage of electronic equipment. Unless this charge is dissipated into the earth it can cause sparks which can lead to fire, or damage electronic equipment.
ESD flooring is meant to release the built-up charge into the earth and keep the floor inert. Thus, avoiding fire hazards and damage to electronic equipment.