content
The Twig-variable {{ content }}
holds the whole content of your Markdown file in HTML.
Example Usage
{{ content }}
You can use Twig filters, but the usecases are limited. For example, you can strip out all tags to get pure text output:
{{ content|striptags }}
You could also slice content or use other manipulations, but in general it makes more sense to create plugins to manipulate content or to add extra content (e.g. with shortcodes).