Why don Brazil and Argentina have their own language?
Most countries don’t “have their own language”. In the Americas, only 2 do: Haiti (with Haitian Kreyol) and Paraguay (with Guarani). Each, however, also has a co-official language (French and Spanish, respectively) that are not “their own”. In Africa, almost no country has its “own language”: Arabic, French, English, Portuguese, Spanish, and Swahili are all shared by other countries. In fact Brazil has many of its own languages, but they are indigenous and generally lack official national status, and in that respect, are similar to most of the other countries of the Americas, Africa, and Asia, all of which have many local languages which lack national recognitionn.