This setting on the event form will control what people have to type on their browsers to reach your event.
The link to your event list will always look like this: eventida.com/event/YOU_SET_THIS
EXCEPT: when you or your webmaster embeds the event on your website - you can share your website's URL. For example, if you are hosting a conference and have a website mysite.com you will likely embed it on a page called "Conference" and the URL will look like mysite.com/conference. Consult your webmaster or content manager for details.