erpnext/erpnext/templates/emails/holiday_reminder.html

<div>
    <span>{{ reminder_text }}</span>
    <p class="text-muted">{{ message }}</p>
</div>

{% if advance_holiday_reminder %}
    {% if holidays | len > 0 %}
    <ol>
        {% for holiday in holidays %}
            <li>{{ frappe.format(holiday.holiday_date, 'Date') }} - {{ holiday.description }}</li>
        {% endfor %}
    </ol>
    {% else %}
    <p>You don't have no upcoming holidays this {{ frequency }}.</p>
    {% endif %}
{% endif %}