The k,p,k is in parenthesis to denote that it is a single action. So, in the next stitch you're going to work, you knit the st, but DON'T slip it off the left needle. Then you bring your yarn to the front and purl the SAME stitch (don't slip it off the needle yet). Then you take your yarn back and knit into the stitch again. Now you can slip the stitch off your left needle. It's going to feel weird and probably tight by the end of it. Try to stretch the stitch out some with your right needle before you start the k,p,k. After that, you purl the next 3 sts on your left needle together, not the ones on your right needle that you just worked. Good luck.