Do you have either Redmi 3 or Redmi 3 Pro with locked bootloader bought from China? Then most-likely you have China Stable version of MIUi 7 running on it with no chance of changing its UI to your own local language. The only possible option you might previously have was flashing custom ROM. On the other hand, flashing custom ROM or even flashing stock MIUI Fastboot ROM requires you to have unlocked bootloader.
Luckily, a senior member of MIUI forum called ManhIT has managed to create a custom build MIUI 7 stock ROM flashable on locked Redmi 3 / Pro. The ROM is Multi-language but basically its based on Stable one and the whole features are just the same. Some credits belong to ManhIT while others belong to Xiaomi.
Key features :
Compatible for Redmi 3 and Redmi 3 Pro with locked bootloader.
Several Global languages are available to choose.
It has all stock MIUI ROM features.
Based on Android 5.1.
Official download page : http://en.miui.com/thread-284309-1-1.html
Mirror download link stored in our US based server :
File name : ManhIT_Redmi3.PRO_Multi_6.5.12_v7-5.1_Global_Locked_UL.zip