Instrument rating refers to the qualifications that a pilot must have in order to fly under instrument flight rules (IFR). It requires additional training and instruction beyond what is required for a private pilot certificate or commercial pilot certificate, including rules and procedures specific to instrument flying, additional instruction in meteorology, and more intensive training in flight solely by reference to instruments.
It's a good thing to have in case you need it if the weather is less than visual conditions. Also it’s an another important step to a career in aviation. Additionally, you can increase the productivity of your personal or business flying.