Hi Oziris,
I think you should be able to override this here: Theme Reference - Cart Summary Item – Snipcart Documentation
There is this part of the template which renders the quantity
<span class="snipcart-cart-summary-item__quantity snipcart__font--slim">
{{ $localize('cart_summary.quantity') }}{{ item.quantity }}
</span>
You should be able to change this into
<span class="snipcart-cart-summary-item__quantity snipcart__font--slim">
{{ $localize('cart_summary.quantity') }} {{ item.quantity }}
</span>
to achieve what you need. Note the space between the two mustaches. You can find info about how to override templates here: Customization – Snipcart Documentation.
I hope this helps!
Best wishes,
Julian