Mario, there is no directory en-ES.

You have to put ini file in:
1. public_html/language/es-ES and
2. administrator/language/es-ES

The name of your file has to be
es-ES.com_jsjobs.ini
downloaded from their site in a language section

That way translation will work in admin and frontend part.
If you see something not translated, open your ini file and add it like this
Word="Palabra" (this is example).

Some things you can translate in modules, and some you can add (if needed) in languages-overrides in your Joomla admin.

Goodnight .
Thanks for your advice.
I have placed the file Es-es.com_jsjobs.ini in both directories.
administrator / languages / ES-es.com_jsjobs.ini
languages / ES-en / ES-es.com_jsjobs.ini

and yet, the translation is not visible.

mariovasquez.com.ve

I have worked with the loggie plugin and detected a syntax error in GB-en.com_jsjobs.ini. I corrected it and also changed the symbol # by; for comments.

I can not think of anything else.

Do you have any other idea of where my error is?

Thanks in advance.

Mario R. Vásquez S.

OK, now you have to make a multilingual Joomla site, no matter if your jobs are going to be only in Spanish. Joomla is by default English, probably you have installed it in Spanish, but for jobs platform to accept and detect your Spanish .ini file, you have to put your menu items, articles, categories, modules to have a little ES flag. More important: your site language in languages selection and in language plugins have to be designated as Spanish.

The producer claims that it is enough to designate Spanish as the main language in the admin panel, but go with these steps: docs.joomla.org/J3.x:Setup_a_Multilingual_Site

So, no matter if you don't have a second language, but jobs platform must get Spanish that way. Then you have to revise the whole thing again, to see if something is left untraslated, and do as I descripted in my first comment.