Two pickers at the top of every page set the language and the currency you see. They change only how things are shown: what you pay and your wallet stay in US dollars.
Open the language picker, which shows English, and choose one of the seven languages. The page reloads in that language.
In Arabic and Persian the panel turns right to left and the product titles are translated.
Open the same picker and choose English. Your choice is remembered from page to page.
Open the currency picker, which shows USD, and choose another, such as EUR.
Net prices in the panel and your wallet stay in US dollars. The currency you choose is used on the public pages of the site.
Tip. Showing the panel in your client's language is a quick way to check how a product's title reads for them.