By default the language blogspot used when you registering to blogger is a language that is based to your location. If you live in USA then google UI will display in English language.
To set the interface language on google, you can change it from your google global account. However, the user interface on your blogspot have to be based on your visitor/country target audience. Now to do this, go to Settings —> Language and Formatting.
In addition you can also translate the blog post from English to other language that is available in the menu transliteration.
Once it’s activated, later when you editing a blog post, or start a blog posting, it will appear as transliteration, like picture below:
Next is Formatting. What is meant here is the format of the time zone, the date header, timestamp, and timestamp comments format.
When you finish, don’t forget to click on Save Settings button.