Simply put, the more people who can find and use your mobile application in their native language, the larger your potential market. But launching a multilingual app and keeping it updated is a challenge - one that requires agility and speed.
Before you start translating, there are business decisions to be made. What languages will you use? What content in the app will be translated? Who will handle the actual translation? Once those are resolved, you need to apply best coding practices and tools to streamline translation and prepare your app for the global market.