I have installed Visual Studio 2017 RC, and by default it set language to my system language (Polish) so I was trying to change it to EN but in Options > Environment > Inter
In RC2 (and most likely in the final release) you can switch language from inside Visual Studio and you can modify your setup to include other language packs.
You can now add and remove multiple user interface languages at any time using the Visual Studio installer on the Language Pack tab. You can select the current user interface language among those installed using Tools > Options > International Settings. Source : https://www.visualstudio.com/en-us/news/releasenotes/vs2017-relnotes#vside