WPML String Translation Addons

Anything that doesn’t fall inside posts pages or taxonomy goes into String Translation. This includes the site’s tagline general texts in Admin screens widget titles and many other texts.

A complex site may contain many strings to translate. Use the display filter at the top of the String Translation page to determine which strings to display.

• Which strings to display – choose the translation status (everything translation complete translation needed or waiting for translator)
• Strings domain – WPML organizes strings into different domains making it easier to find a specific string. If for example you are looking for a widget string select the Widgets domain
• Search – you can enter a search value to narrow down specific strings

Demo Link : https://wpml.org/documentation/getting-started-guide/string-translation/

Summary from Demo
WPML String Translation allows you to translate texts that are not in posts pages and taxonomy. This includes the site’s tagline general texts in admin screens widget titles and many other texts.
WPML’s String Translation module is part of the Multilingual CMS account type. To enable it you first need to download and install it from your WPML.org account under the Downloads section.
Then navigate to WPML → String Translation.
A complex site may contain many strings to translate. Use the display filter at the top of the String Translation page to determine which strings to display.
Many strings are already loaded into the String Translation table ready for you to translate. However WPML does not automatically load every single string. If you can’t find a particular string you would like to translate please see our article about finding strings.
Once you have located a string you would like to translate click the + icon under the flag of the language you would like to translate it into.
You can save your translation by hitting the Enter or Tab keys on your keyboard or simply clicking out of the window. The Tab key allows you to switch between languages without having to click.
You can also send strings to your translators. Click the checkboxes next to strings select the languages from the list and add the strings to the translation basket.
Assign the translation job to yourself or a local translator to translate the strings using the Advanced Translation Editor. You can also send the job to be translated by a translation service.
When you no longer use a certain theme or a plugin you might wish to remove the strings associated with it. Simply select the strings you want to remove and click Delete selected strings.
To delete all the untranslated strings belonging to a certain domain scroll down to Remove strings by domain and click Remove strings. Select the domains of strings you don’t need anymore and click Remove. The untranslated strings in these domains will no longer appear on the String Translation screen.
You can always add the strings again by going to WPML → Theme and Plugins Localization. Choose the plugin or theme and scan it to make its strings available for translation again.
If a theme or plugin you’re using is coded in a language other than English WPML may miscategorize the source language of strings. Please see our documentation on how to change the source language of individual strings and entire domains on the String Translation page.
Theme and plugin authors are encouraged to include a language configuration file in their code which tells WPML which strings from the wp_options table to register for translation. This can save a lot of time for end users configuring multilingual sites.