It's the VAT collected by some of the European countries. The VAT is determined in your list price and paid so there isn't extra paperwork if you're selling ebooks via Amazon European facing web properties.
When you set your List Price for our EU websites, you have to factor in the additional 3% value-added taxes (the Luxembourg statutory rate effective January 1, 2012) we will add for EU customers, so that your List Price complies with this section after adding these VAT taxes.
https://kdp.amazon.com/self-publishing/help?topicId=A29FL26OKE7R7BSame concept applies for books in a bookstore unless you're going through a publishing house they should be taking care of it as well.
Always a good idea to confirm with an accountant.