Insulation is the process of keeping heat, sound, or electricity from spreading. It's also the material used to do so. If you can hear your neighbor snoring at night, you might need better sound insulation.
Your thermos of hot chocolate stays warm when it's freezing outside because the thermos provides insulation. Similarly, the insulation in an ice chest keeps your sodas and food cool at the beach, even when you're being scorched by the sun. Insulation can also refer to a state of being detached or isolated. If you stay at home and avoid TV, the internet, and phone calls, you are in a state of insulation.