There is a separate module called angular-translate that lets you define localizable strings and a filter to retrieve the correct string from the current locale to display in your view. I'm not sure what you mean by "single language file", but this supports entering strings in your config via a table or loading the strings for a locale from a file.
Simple example from the guide (loading strings from a table):
var app = angular.module('myApp', ['pascalprecht.translate']);
app.config(['$translateProvider', function ($translateProvider) {
$translateProvider.translations('en', {
'TITLE': 'Hello',
'FOO': 'This is a paragraph',
});
$translateProvider.translations('de', {
'TITLE': 'Hallo',
'FOO': 'Dies ist ein Paragraph'
});
$translateProvider.preferredLanguage('en');
}]);
In your view, just use the filter syntax:
<h1>{{ 'TITLE' | translate }}</h1>
<p>{{ 'FOO' | translate }}</p>