Translate „read more“ in WordPress

Hello, it was so much searching and “googling” and trying…
In my case, it meant editing the filecontent-widget-blog.php
inwp-content/plugins/flash-toolkit/templates
and change theRead MoretoČÍST VÍCE
(this is Read More in my default language settings)
in this line:
<a href="<?php echo esc_url(get_permalink() ); ?>"><?php esc_html_e('ČÍST VÍCE', 'flash-toolkit' ); ?></a>

Translate „read more“ in WordPress