Every module which supports localizaton includes an App_LocalResources folder where the Resource Files reside.
So the file which supplies the text in English for the 'US" for the submit button is called "FormMaster.ascx.resx"
Now if you want to supply another language for example German, you copy that file and name it "FormMaster.ascx.de-DE.resx" and change the Values for the Names to German.
Once you have done this for all the files in that folder for the New Target Language, then Form Master will just follow the Localization Rules supported in DotNetNuke.
If those files are missing, even though you have DotNetNuke set up to be Localized, the system will just fall back on the default English for Form Master.