The verb insulate means "protect from heat, cold, or noise," like when you add an extra layer of clothing to insulate yourself from the cold.
You can insulate a wall to keep sound out, or insulate your house to keep cold air from getting inside. So, to insulate is to protect against unwanted changes. Sometimes this can mean keeping out the influence or beliefs of other people, like a parent who tries to insulate his children from people who have different cultures or beliefs. You can see this meaning in the origin of insulate: the Latin word insula, meaning “to make into an island.”