Uncapping is the process where your honey is released from the wax cells ready for extracting. The easiest method is to scrape a hot knife over the capped cells to remove the wax allowing the honey to drip out. When you have a large number of supers to deal with then, of course, an extractor comes in very handy. This useful machine will free your honey with minimum effort on your part.
If you are dealing with manuka or other very thick honeys (such as heather) an uncapping pricker is necessary as it will agitate the honey to loosen it and make it easier to extract. It also preserves the wax comb so that the bees can fill it again quickly. (This applies especially in the middle of the honey flow).
The wax cappings you remove can be pressed then melted down to obtain the beeswax.