Having a multi-language store in Magento 2 is a great advantage, especially if you also manage a blog. It's a perfect way to share your content with a global audience.
Yet, to complete this task you have to translate your blog for all store views you have. That said, the translation of blog categories in Magento is something you'll have to deal with.
To translate blog categories in Magento 2:
1. Navigate to Content > Blog > Categories and select the category you want to translate.
Note: you need to create a new item to translate a category in Magento. So, you have two options: create a new category by pressing the Add New Category button or Duplicate the existing one and proceed with the translation.
2. Set the Enable Category option to Yes.
3. Translate the Category Title and select a corresponding Parent Category, if you have any.
4. Add a translation of the category Content.
5. Go to the Category in Websites section and choose the Store View you want this category to be displayed on.
6. Move to the Search Engine Optimization section and fill out the fields you have here.
7. Look through the rest of the sections to make sure all content is relevant.
8. Press the Save button and check your category on the front end.
Pro tip: you can also add hreflang tags to your blog category page. This way you define that you have multiple pages in the alternative languages. So each of them will be ranked by search engines separately.
Once you translate blog categories in Magento 2 you're good to move to the next step which is translating your blog posts.