Click the start menu, and type in printers, then click Devices and Printers from the suggestions list.

Right click the printer to share, and click Printer properties.

(Note that here, we are using the generic / text only printer as an example. Yours will be called something like Label Printer)

In the sharing window, click the Sharing tab.

Tick the Share this printer checkbox, and give it a name, something like LabelPrinter. Note that you should avoid using spaces or symbols for compatibility.

With the printer itself shared, we now need to tell Windows to let the PI connect.

To do this, click the arrow next to Control Panel, near the top left of the Devices and Printers window, and click Network and Internet.

Click Change advanced sharing settings, which can be found on the left.

It gets a little trickier here. This is split into sections, usually named things like "Home or Work" and "Guest" or "Public". Each section needs to be expanded in turn, then file and printer sharing set to on, and password protected sharing set to off.

Finally, click Save changes.