To edit POS Receipt/Bill Goto Odoo : C:\Program Files (x86)\Odoo 12.0\server\odoo\addons\point_of_sale\static\src\xml\pos.xml
Open pos.xml and place following code in receipt-orderlines class
<table class='receipt-orderlines'>
<colgroup>
<col width='50%' />
<col width='20%' />
<col width='15%' />
<col width='30%' />
</colgroup>
<tr>
<th>Item Name</th>
<th colspan="2">Rate X Qty</th>
<th colspan="3">Amount(NPR)</th>
<th colspan="4"></th>
</tr>
<tr t-foreach="orderlines" t-as="orderline">
<td>
<t t-esc="orderline.get_product().display_name"/>
<t t-if="orderline.get_discount() > 0">
<div class="pos-disc-font">
With a <t t-esc="orderline.get_discount()"/>% discount
</div>
</t>
</td>
<td class="pos-left-align">
<t t-esc="orderline.get_unit_display_price()"/>
</td>
<td class="pos-center-align">
<t t-esc="orderline.get_quantity_str_with_unit()"/>
</td>
<td class="pos-center-align">
<t t-esc="orderline.get_display_price()"/>
</td>
</tr>
</table>
Output : Please refer attached image
Best,
Ram