Earlier we don’t have permalink option in blogger. Whenever you publish a new blog post blogger creates an url for your blog post. Normally this url will be created from post title as shown in below pic.
Permalink for Blogger Blog Post
But now you can customize your blogger blog post url using Permalink option. In blogger post editor you’ll see Post Settings to the right side of editor under which you can see Permalink option. Click on custom URL, type the url you want and then click done. Allowed characters are a-z, A-Z, 0-9 and a dash(-).
This is also one of the search engine optimization which can improve traffic to your blog post. From above 2 images you can clearly see the difference in the urls.