For this instruction forget what you did to the stitch on the previous row and only look at the stitches that you're about to do. Look at your knitting and make a knit stitch, then turn it around and look at it on the other side, then do the same with a purl. The back of a knit stitch is a purl, the back of a purl is a knit stitch. But a previous row is already done, and you just work the stitches the way they look on this row.