All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad is His slave and Messenger.
We are not aware of the language of jinn, however, Shaykh Ibn Baaz was asked this question and he answered as follows:
“What appears to be the predominant opinion is that they are like humans, in that they have various languages. Amongst them there is the English (jinn), the French, the American and amongst them there is the non-Arab and the Arab. They are of different races because Allaah says concerning them (what means): {There are among us some that are righteous and some that are contrary; we are groups having different ways.} [Quran 72:11]
And they are different in sects; Allaah Says (what means): {And some of us are Muslims and some of us are Qaasitoon (disbelievers).} [Quran 72:14]. Thus they have different groups and sects: amongst them there is the good and amongst them there is the bad…. Amongst them there is the Christian, the Jew and other than that. They are divided into different kinds and groups; Allaah Says (what means): {There are among us some that are righteous and some that are contrary; we are groups having different ways.} [Quran 72:11]. Allaah’s statement: {…some that are contrary} is general and includes other groups."
Allaah Knows best.