Upload Po file into server – Where is it?

We translate to spanish with loco translate, but it don’t work.
We donwload the “PO file” to inject the words in spanish like this:

#: inc/woo-giftcards-class.php:82
msgid “Resend Email”
msgstr “Reenviar email”
“Reenviar email\n”

Now ?where is the directory by ftp, to update the file?

The page I need help with: [log in to see the link]