What is the name of movie where American Indians used their native language to confuse Germans?

The movie you are referring to is called "Windtalkers". It is a war film released in 2002, directed by John Woo and starring Nicolas Cage, Adam Beach, Christian Slater, and Roger Willie. The film is set during World War II and tells the story of a group of Navajo code talkers, who were American Indians who used their native language to transmit coded messages for the U.S. military during the war. The code was unbreakable by the Japanese and played a vital role in the success of the U.S. forces in the Pacific theater of operations.