When you pulverize something, you break it up until it becomes dust or powder. You might pulverize coffee beans in grinder, running it until the coffee turns to powder.
Pulvis is the Latin word for "dust." When something is turned into dust, often it becomes useless. That's why pulverize can also mean "to destroy or demolish." Construction crews pulverize a building using wrecking balls and sometimes even explosives. The materials left behind are broken into such small parts that they can't be salvaged for other uses.