I'm pretty sure it means, do 19 rows of stocking stitch (alternating rows of purl and plain/knit), starting with a purl row. So do 19 rows, all the odd rows including the first are purl stitch, all the even rows are plain/knit stitch.

Thank you very much colleenoz! Another person said the same thing so odds are very good you both are right! Can't wait to get started on my first ever knitting project.