Havaianas is a Brazilian brand of rubber sandals. The shoes are flip-flops and related sandals, with the brand’s textured footbed, sold in adult and children’s sizes. This storefront is the Asia Pacific one, so the sizes, the currency, and the shipping countries are the ones that shop serves.
A style differs by color, by whether it has a printed strap, and sometimes by a platform or a closed toe. The size chart is in Brazilian and local sizes, and the product page shows which scale that shoe uses. A pair bought from the Asia Pacific shop ships under that shop’s delivery rules, which are not the same as a shop in Brazil or Europe.
The collection is sandals, not a full clothing line. Width and the footbed shape are the Havaianas last, so the size chart on the page matters more than a size from another shoe brand.