This is technology engineered to be smaller than visible to the human eye with the word Nano meaning Nanometre. Already motors, sensors and microcircuitry has been created on this scale, but not in any usable amount.
This technology will revolutionise our world. At first, chip fabrication will become easier, cheaper and more capable. Engineering and synthesis of chemicals like paints and polymers will become easier, and we will see great advances. Eventually, we will have Nano Bots.
It is through nano tech that we will have items like a Star Trek replicator which could produce usable material from waste or raw material extremely efficiently.
Some people are fearful of this, and worry that the Nano Tech devices will be more like the Stargate Replicators. I see this as unlikely as the intelligence needed to behave like these is a greater than that needed for manipulation of molecules. The repeatable blueprinted process is more like a sophisticated 3d printer than a self replicating robot.
Once we have nano-scale manipulators, recycling will also become an increasingly viable option in cost and efficiency.