To hold a license in New Zealand you must be assessed to be proficient in speaking, reading and understanding English.  All international students are also required to meet IELTS level 6 or have four years of secondary schooling where instruction and all learning activities have taken place in English, and at least 14 Level 3 credits in an English-rich subject (English, History, Art, Geography, Biology, Classics, Art History, Journalism, Media Studies, Religious Studies, Physical Education).
Note: Your instructor will assess your English as you learn to fly and all pilots must pass a formal test before applying for their licence.