ExpressionEngine not gives default URLs for the channel entries. We often use Pages or Structure module for that. If you are not using any of these module, your page URL could be anything. This is the setting page to declare the URLs of those channels. You can set the patterns and other will handle by us.

You can add pattern to all channels. You can use this tags in patterns {entry_id}, {url_title}, {category_url_title}, {category_id}

If You are not adding anything in the URL pattern, We will look into Channel preferences and look for the pattern there. If that place is also empty, We will show a link as url_title only. /{url_title}