Amazon PPC stands for "Pay-per-Click", an advertising model to bring traffic on the product detail page. The seller pays only when the advertisement is clicked.
Basically it's a way to get more traffic to the product page that wouldn't come from organic search.
Various pay-per-click solutions are available for Amazon sellers: Sponsored Product, Sponsored Brands and Product Display Ad.
The product will appear in the search results (or in other placements on the Amazon site) if the search term of the buyer match a keyword entered by the seller. This type of results differ from the non-paid results (called organic) by the quote "Sponsored".
The average cost of a click over a time period is
CPC = Total advertising cost / Clicks
Amazon's advertising platform uses a bid-based CPC system.
Sellers enter keywords to Amazon Advertising (or Amazon Seller Central) on which they want their products to appear and how much they are willing to spend for a click. When the buyer searches a term on Amazon, the system quickly develops an auction model to decide which products to appear and in what order.
To decide how to order the results Amazon takes into consideration the bid per click (provided by the seller) and the probability of click (calculated by Amazon based on the relevance of the product and historical data). The seller is charged a cost of at least one cent higher than the competitor of lower position, but at most what he indicates in the bid per click.
To obtain good results, sellers or agencies often use ppc automated management systems to handle bid per click. Advigator is one of these focused 100% for Amazon, which analyzes the data daily to better adapt the bids for all keywords and products based on their conversion rate.