The default url for WordPress.org post use the date and the post name.    A better url contains a keyword instead of a date.    A date can only make your post look old after a few months.   But by adding the category you will get a url that has more keywords and can be found easier on Google.

This is really easy to do.  Simply edit your Setting and select permalinks.  Make the custom structure to be

"/%category%/%postname%/"