Blocks represent single parts of your Sylius web app, where you can put some content hardcoded in the template and change it in the future from admin panel.
In the admin panel, you can create block resources. It could be rendered in your twig templates using
bitbag_cms_render_block([block_code]) helper extension. For instance, let's assume you created a block with
homepage_intro code and want to render it on store homepage. In your
app/Resources/views/SyliusShopBundle/Homepage/index.html.twig file add the Twig filter like this: