The Non-European Mobility Programme implies the knowledge of the language of teaching of the host institution (it is not a language learning programme).
Indeed, host institutions have language requirements in order to be accepted as exchange students. In general, except in Spanish-speaking universities, the selected students must have a linguistic knowledge of level B2.2 - C1 (TOEFL, IELTS, DELF, etc.). The specific information of each host university can be found on its website, in the section on international exchanges.
In relation to the English language, international accreditation of their more English titles widely defendants are TOEFL, IELTS, MELAB.
In relation to the French language, the most demanded international titles are TFI, DELF B2, DALF.