.US File

File extension us is sometimes used by various programs as English (American) language translation file.

Often uses simple text format or XML structure and it is viewable and editable in text editing software.

How to open:

Use Notepad, Notepad++ or another text editor.

How to convert:

It is unlikely direct conversion tools for .us files exist, but perhaps simple manual editing and resaving using a text editor might be enough for your purposes.