Xenoglossy is either knowledge of a language one has never learned, or the act of speaking a language one is not familiar with.

xenoglossia

xenoglossias

xenoglossies

xenoglossy

The term is glossolalia, also known as speaking in tongues. The speaking in actual foreign languages is known as xenoglossy.

See http://en.wikipedia.org/wiki/Glossolia

and

http://en.wikipedia.org/wiki/Xenoglossy

A xenoglossy is a person with the ability to speak a foreign language without learning it. A xochitl is a large, blue flower.

Experiencing a trance and speaking another language could be a manifestation of a dissociative state or a phenomenon known as xenoglossy, where a person speaks a language they have not consciously learned. It could be a result of subconscious processes or suggest a deeper connection to the language or culture being spoken.