As Symfony2 said, everything in the framework is bundle. So, your website will also be a bundle. As far as I could understand from http://symfony.com/doc/current/cookbook/bundles/best_practices.html, bundle represents a feature, and that means everytime I want to add a new feature, I must create a new bundle.
For example, I want to create a website which have Blog features and Event Features. Then I will have 2 bundles, BlogBundle and EventBundle. Every code related to Blog will be housed under BlogBundle, and Event in EventBundle.
My question is, where should I put the homepage? or maybe another page like Contact, About, Terms and Policy, etc...?