Unfortunately, you must pair Excel with Word to make it so you can use a wizard to guide you through the process. Assuming Addresses.xlsx is your spreadsheet containing addresses and Labels.docx is a blank new Word document:
In Labels.docx, select the Mailings ribbon and click the Start Mail Merge dropdown, then select the Step by step mail merge wizard. In the panel that opens up on the right pick Labels, then click Next.
Label options...
Select the vendor that matches the one on your box of labels, then select the Product number (also found on the box). [OK]
Back to the panel - - - Next
* Use existing list
Browse... to Addresses.xlsx and open it. Uncheck the box if your address spreadsheet doesn't have column headers. [OK] , then select the addresses you want for your labels. [OK] , then Next.
Click Address block... Play with the options until the preview looks the way you want it.
[OK] If you want all your labels in the same format, click [Update all labels]. It's time to preview your labels so hit Next. If you want to preview more than just the first page of labels, on the Panel: [>>]
I don't usually care for all the space between each line on the labels, so I click the little box in the upper left corner of the page to select all the labels, go to the Home ribbon, Paragraph section, change the Line spacing to 1.0 AND remove the space before (and after) paragraphs. Next, then Print if everything looks good.