Install libreoffice-l10n-vi by entering the following commands in the terminal:
sudo apt update sudo apt install libreoffice-l10n-vi
office productivity suite -- Vietnamese language package
LibreOffice is a full-featured office productivity suite that provides a near drop-in replacement for Microsoft(R) Office. . This package contains the localization of LibreOffice in Vietnamese. It contains the user interface, the templates and the autotext features. (please note that not all this is available for all possible languages). You can switch user interface language using the locales system. . Spelling dictionaries, hyphenation patterns, thesauri and help are not included in this package. There are some available in separate packages (myspell-*, hyphen-*, mythes-*, libreoffice-help-*) . If you just want to be able to spellcheck etc. in other languages, you can install extra dictionaries/hyphenation patterns/thesauri independently of the language packs.