To use the polisher, you attach it to the end of the wands, just like the floor brush, and attach the hose to the SUCTION end of the Electrolux. When you turn on the motor, the suction will cause the polisher's inner star-shaped brush to rotate rapidly.
Originally, you could polish any hard-surface floor -- hardwood, tile, cork, masonry, etc. However, nowadays most floors - including hardwood - are usually sealed with some sort of coating that does not need to be machine-polished. If you live in an old house with original unsealed hardwood floors, you can use the polisher with any liquid or paste floor wax. Some hardware stores still carry it or you can look for it on line.
The set of black brushes is for applying wax and the set of brown brushes is for polishing. Did you also get a lambswool buffing pad? That would be used to impart a final glow to the polished finish.