Listed different options how your URLs can look.
It comes either from core url system or plugin e_url addon with defined profiles.
Remove file name from URL
Removes entry script file name (index.php/) from your URLs. You'll need mod_rewrite installed and running on your server (Apache Web Server). After enabling this setting go to your site root folder, rename htaccess.txt to .htaccess and modify "RewriteBase" Directive if required.
Associate Root namespace
Choose which site area will be connected with your base site URL. Example: When News is your root namespace http://yoursite.com/News-Item-Title will be associated with news (item view page will be resolved).
For example, you usually have path yoursite/page/page-sef-url. if you select page, then page alias is removed from URLs and you get URL yoursite/page-sef-url. The same for news
Warning: you get 404 look/result for page, not system 404 page
Redirect to System not found page
error.php is displayed directly, not pretty URL. It doesn't work with page root. If set to false, not found page will be direct rendered (without browser redirect)
SEF string creation type
Choose how will be assembled SEF string when it's automatically built from a Title value (e.g. in news, custom pages, etc.)
The most important setting. It uses for generating SEF URL (slug) from for example title. In Admin UI (custom plugin) you can set the source for generating slug.
Overview of all available e_url addons.
If there is an option to change the alias, then the alias name is editable.
You can set different alias name for each language.
It is something like a taxonomy slug in WordPress. You can set the different alias (slug) for each e107 part of the core and you can them differently for each language.