Guarani is one of the official languages of Paraguay, along with Spanish. Guarani is spoken by the majority of the Paraguayan population. This is unique, since after the colonization of countries in America, most countries experienced a language shift, adopting European Colonial languages (like Spanish). Paraguayans were able to maintain their native language while also adopting Spanish.
source: https://www.ine.gov.py/news/25-de-agosto-dia-del-Idioma-Guarani.php