Address Labels Template On Pages?

You could use the Contacts application, import an Address CSV from Numbers into a custom group, select all members of that group, and then print a sheet of Avery labels from that group selection. Discussed in Contacts User Guide.

Since no version of Pages since 2013 has built-in Mail merge, you are better off with the first paragraph. Otherwise, you could download a blank Avery template in Pages document format, and fill it with manual labor. On that Avery page, just click the image of the label, and the next page will provide the Pages template for it.