The Earth maintains a negative electrical potential on its surface. When we are in direct contact with the ground (walking, sitting, or laying down on the earth's surface) the earth's electrons are conducted to your body, bringing it to the same electrical potential as the earth. Living in direct contact with the earth grounds our body, inducing favorable physiological and electro-physiological changes that promote optimum health. Our body contains different fluids which contains various ions. The cells in our body also contain many ions. Therefore, our body is a good conductor of electricity.
When we are bare-footed, our body is directly in contact with the earth. When we touch wires carrying electricity, we may come in contact with a live wire. The current passes through our body to the earth & we get a shock. Hence, we should wear shoes with rubber soles (insulator) and the given statement is true.