What is the message at blog about Cookies notification in European Union countries?

European Union (EU) laws require you to give EU visitors information about cookies used on your blog. In many cases, these laws also require you to obtain consent.
Stated below is what the message appears like -
As a courtesy, we have added a notice on your blog to help meet these regulations. The notice lets visitors know about Google's use of certain Blogger and Google cookies on your blog, including Google Analytics and AdSense cookies. Learn about Google's privacy practices and how Google uses data on partner sites.

As said in the previous answer you can find that Google is modifying the blogger and their other properties with these new changes.

EU requires the people around the world to show cookie consent message at the top or bottom of the website.

This is to show people that cookies are collecting the personal data from the user browser.

Google adsense also issued the notice that by the end of the October, blogs who get traffic from EU should have such cookie consent notice on the blog.

If you are normal user then just click on accept button or okay button on that Cookie consent notice. If you are developer and haven't added such notice then you should install it before October.