Gang labels onto one page the way you'd gang a print sheet. Type one label per line, pick a layout, and get a 300 DPI page ready to print onto label stock or plain paper.
Test on plain paper first. Every printer shifts the page a little, and label stock varies by brand and batch. Print one page on plain paper, hold it against a real label sheet up to a window, and adjust the offsets before you feed the good stock through.
What goes on them
In "one label per line" mode each line becomes its own label, and the page fills as far as the lines go.
Layout
Output
The PNG is a full 8.5 × 11" page at 300 DPI (2550 × 3300 px) with the resolution written into the file.
Preview is to scale. Guides show where the labels sit — they're never included in the downloaded file.