The Community Edition Language File is a text document (*.txt) that is placed in the 'language' folder in the installation folder. It contains a list of original text vs. translated text which will replace words and phrases used throughout the program.
Here is an example file with the standard English language set as shown below that you can download and edit (please unpack from zip first): gb.txt
The columns are separated with the '|' character.
e.g. a default GB language file 'language\gb.txt' would contain:
Original Text|Translation Yes |yes No |no OK |ok Cancel |cancel Close |close Rename |rename Delete |delete Default |default Save |save Options |options Exit |exit Window |window New |new (etc)
Note that if using extended characters you will need to save the .txt file as Unicode. In Notepad you can select the Encoding when you save, as in the following screenshot.