Doubt about Language Module

Hi Team !

I have a doubt about the language module, I am doing the site in Spanish and it worked fine, however I see that most of the menus are still in the original language (English).

When I examine the en.xml file I notice that it only contains 3175 records and that it does not contain all the keywords to be translated for the site. 

I also notice that in the "Navigation" module there are some translation options, but I would like to do this task directly from the Language file (.xml). 

How can I do the full translation of the site from the "es.xml" language file?

Thanks for your prompt help!