Code to show the quantity, insert the code on product-template.liquid normally it will be on the line number111

<div id="variant-inventory">
{% if product.variants.first.inventory_management == "shopify" %}
{% if product.variants.first.inventory_quantity > 0 %}
We currently have {{ product.variants.first.inventory_quantity }} in stock.
{% else %}
The product is out of stock
{% endif %}
{% else %}
This product is available
{% endif %}
</div>