Once an invoice is generated for an order, you can print it by using 'Print Invoice' option.
Go to Orders > Orders section in StoreHippo Admin Panel. To print an invoice, either click on the vertical ellipsis icon there you will get the 'Print Invoice' option, else click on the order ID to open the order details in the right panel, there you can click on the ellipsis icon to get this option.
Clicking on this option will open the invoice in pdf format in a new tab, from where you can download or directly print the invoice.
You can also print invoices for multiple orders at the same time by selecting the orders for which you want to print invoices.