As stated in creating a blog, you can publish the blog posts for every language all at once. If you don't want this blog to be available (yet) in one or more languages, you can publish a blog post for a single language!
If you add or edit a blog, go to the section posts. Use the tabs to go to the language you want to make a blog post for and fill in the title, description and blog post. You see an orange box on top of the form where "post (language) is not published yet" is written. Luckily, the box contains a button to publish the blog post for that language. Clicking on that will also save everything you changed for this blog.
Unpublish a Post
Not happy with the blog post? Or is the blog post not relevant anymore? Or maybe you just want it to temporary invisible? Well, don't worry too much! The orange box turned green, and contains a button for you to delete the page. This will not delete your blog post permanently, but will make sure the user can not visit it anymore.