The categories.twig view will display all of the categories contained the account (that are not inactive) and that do not have a parent category.

In most circumstances, the categories page will extend the collection.twig template because it's format will follow the usual display of collection pages on your theme.

The categories page has access to the category object which can be used to display details about each category (such as the category name and image) with a link through to the category page, e.g.

{% for category in categories %}
    <a href="{{ category.url }}">
        {{ category.title }}
{% endfor %}