sale_reports.xml

<?xml version='1.0' encoding='utf-8' ?>
<odoo>
    <template id="report_saleorder" inherit_id="sale.report_saleorder_document">
                <xpath expr="//th[@name='th_description']" position="after">
            <th class="text-left">Brand</th>
        </xpath>
        <xpath expr="//td[@name='td_name']" position="after">
            <td name="td_product_brand">
                <span t-field="line.product_id.product_brand_id.display_name" />
            </td>
        </xpath>
    </template>
</odoo>