Each category, section and article has its own unique ID. It does not change and it's the same for all its translations.
In our themes we sometimes rely on this ID to give the category, section or article a unique layout or design, or to be able to find it more easily. We may ask you to provide this ID in theme settings or assets.
To find the ID you can visit the category, section or article on your Help Center. Next, take note of the 12 or 13-digit number that's in the URL. For example, the article you're viewing right now has the following URL: https://guide.premiumplus.io/hc/en-us/articles/4405439361044-Finding-a-category-section-or-article-ID . Its article ID is 4405439361044.
The same principle applies to sections and categories.