Galaxie Blogs URL is comprised using two parts- the Post Date, and the Post Alias.

Take for example the following blog post:
https://gregoryalexander.com/blog/2022/5/20/Introducing-the-Galaxie-Blog-Administrative-Site

The date part, 2022/5/20 in the URL is the Post Date- when the post was created.

The 2nd part, 'Introducing-the-Galaxie-Blog-Administrative-Site' is the title of the blog post, separated by dashes. This is known as the Post Alias. 

The Post Alias is automatically created when the post was made, however, if you don't like it you can change it.

To change the automatically created Post Alias, open the Post Interface, and click on the 'Change Alias' button in the Misc section of the Post Interface. This will bring up a new interface. Enter in a new desired alias, make sure that the new alias does not contain any spaces or special characters, and click on submit. Finally, submit the post and your URL should change.