Sentence examples for a new language from inspiring English sources

"a new language" is a correct and usable phrase in written English.
It can be used to refer to a language that someone is learning or to a language that has recently been created or introduced. Example: "I decided to learn a new language over the summer." (referring to a language the speaker has not previously known) Example: "The government is promoting the use of a new language in schools." (referring to a newly introduced language).