The melting point of a substance referst to the temperature at which it changes state from solid to liquid. Therefore, the statement "The melting point of glycerine is 13 degree celsius" means that when the temperature at which glycerine is subjected is equal or higher than 13 degree celsius, it changes state from solid to liquid.
For example, the melting point of water is 0 °C. It means that when the temperature is higher than 0°C water goes from solid (Ice) to liquid. We all have seen that, right? ✔️
This means the temperature at which glycerine changes from solid to liquid is 13 degrees Celsius.
Melting point of a substance is the temperature at which it changes from the solid state to liquid state. Heat breaks the intermolecular forces of attractions that holds the substance together.The solid and liquid state are in equilibrium at the melting point. The melting point of a substance depends on pressure, shape of the substance, etc.