Text domain is a unique identifier for distinguishing between translations, and identifying which strings belong to what theme or plugin.
How do text domains support multilingual functionality in themes and plugins?
In order for a plugin or theme to be translation-ready, it needs to have a text domain. This makes it easier for WordPress to identify which strings are associated with a specific theme or plugin, streamlining the translation process across multiple languages.
How can I manage the translation of strings from specific text domains on my site?
You can manage the translation of strings from text domains on the String Translation page. In Auto register strings for translation, you can enable the option to Look for strings while pages are rendered.
Clicking Edit shows you all the text domains on your site and allows you to exclude specific text domains from being auto-registered:
Selecting which strings in text domains to register
