To reference the partial page views/partials/some-partial.ejs from a page in views/pages in ejs, use the include function as so:

<p> Here is some HTML </p>
<%- include('../partials/some-partial.ejs') %>
<p> Here is some HTML </p>

This will replace <%- include('../partials/some-partial.ejs') %> with whatever code is in views/partials/some-partial.ejs.

For more information on working with ejs, click here.

For information on what the various distributed partials do, view this tutorial.