Both words are international: Bitcoin needs no translation anywhere, and bank is understood by business audiences in Taipei as readily as in London. Taiwan writes in traditional Chinese characters, so an English address often works as the brand's Latin-script counterpart, printed on cards, apps and statements next to a Chinese name. The .tw ending ties that counterpart to the island and makes the local orientation visible before a page loads.
bitcoinbank.tw is part of the Bitcoin Bank International set; the name is also held on other country endings and generic endings, and the group can be taken over as a package. The address suits a Taiwanese digital bank adding bitcoin accounts, a custody or payments provider serving local companies, or a foreign institution that needs a dedicated entry point for its Taiwan branch.