The name you give a Snippet is how you will refer to it later on in your Templates.
{%- if userName -%}
{{userName}}
{%- else -%}
Someone
{%- endif -%}
{%- for item in list -%}
<p>{{item}}</p>
{%- endfor -%}
{%- load_snippets 'user-name', 'items-list' -%}
<p>Hello {% include 'user-name', userName: "Jane Doe" %}</p>
{% include 'items-list', list: user.groceries %}