If the last five stitches on the row were K3, P2 the next row would begin K2, P3. But what everyone is trying to help you learn is that it is way better not to think about it that way at all. When you turn back to work the next row you should work the stitches as they appear to you ready to be knit. If the stitch ready to be worked has the little "vee" right below the needle you knit it. If the stitch you are ready to work has the bump right below the needle you purl it. I remember it by thinking that pearls are round like the purl bumps.