Add language string in WordPress

Hello there,

Basically I want to change the words “Previous post” and “Next Post” for “Previous Work” and “Next work” in this site: https://fontaneriaborja.com/en/portfolio-view/solar-panels-swimming-pool/

I have gone into /wp-content/themes/CherryFramework/loop/loop-single-portfolio.php and found this code:

<!--BEGIN .pager .single-pager -->
	<ul class="pager single-pager">
	<?php if (get_previous_post()) : ?>
		<li class="previous"><?php previous_post_link('%link', theme_locals("prev_post")) ?>
	<?php endif; ?>

	<?php if (get_next_post()) : ?>
		<li class="next"><?php next_post_link('%link', theme_locals("next_post")) ?>
	<?php endif; ?>
	<!--END .pager .single-pager -->

I believe that theme_locals(“prev_post”) and theme_locals(“next_post”) are the strings that call the text.

Ideally what I would like to do is to change and add a new string for something like theme_locals(“prev_work”) and theme_locals(“next_work”) that would generate two new translations to my .po files. However, is here where I get stuck.

It is a multi language WordPress 4.1.1 site using Polylang and a theme from Template Monster with the cherry plugin.

I have already searched around with no luck to understand how this works. So any help would be really appreciated.

Thank you for your time and thanks in advance to all of you.

Best

P.S.: I am a beginner in terms of web development.