There are 12 different language settings to choose from in Iron Marines: English, Italian, Portuguese, German, Indonesian, Spanish, Russian, French, Korean, Japanese, Simplified Chinese, and Traditional Chinese.
To change your language settings
From the map, go to the Settings menu by tapping the gear on the bottom right
You'll find the Language settings on the middle left, tap it to see the options.
Select your language of choice, then tap DONE.