Base on your code and according to that you want to get Count of rows in Qty column you can try
<table class="tablesorter">
<thead>
<th>DA</th>
<th>Part</th>
<th>Batch</th>
<th>Qty</th>
</thead>
{% set row_count = 0 %}
{% for getbatches in getbatch %}
<tr>
<td>{{getbatch.dano}}</td>
<td>{{getbatch.partno}}</td>
<td class="highlight">{{getbatch.batchno}}</td>
<td>{{getbatch.inqty}}</td>
</tr>
{% set row_count = row_count + 1 %}
{% endfor %}
</table>
if you want to show that amount somewhere (like a span) you can use <span>{{ row_count }}</span>
after
UPDATED
A better solution to show the rows count anywhere if your twig template might be just showing the count of getbatches
:
<span>Row count: </span><span>{{ getbatches is defined ? getbatches|length : 0 }}</span>