• internationalization(i18n): The process of designing a software application so that it can be adapted to various languages and regions without engineering changes.
• localization(l10n): The process of adapting internationalized software for a specific region or language by translating text and adding locale-specific components.

See:

• Internationalization vs. localization (i18n vs l10n): The differences

VS Code extensions

Using VS Code API l10n

GitHub: microsoft/vscode-l10n