You might be in a match that was set in another language. Please be careful when you accept game invites as the match might be set in a language you do not speak. Meanwhile, you can set your preferred match language. To do so, follow the steps below.
Here is how:
1. Tap on "Start a new game"
2. Tap on the button in the upper right corner of the screen that displays your current language
3. A menu of available languages will appear, tap on the one you wish to change to.
Please note that the language in the app syncs with the language settings of your mobile device