Purl: (P) This is used often, and is quite simple once you get the hang of it. It is basically the opposite of a knit stitch. Put the knitting tool through the loop on the peg from top to bottom, grab the working yarn with the tool, pull it up through the loop and remove that loop from the peg, and put the new loop you just formed onto the peg. Be careful not to pull too tight, keep the working yarn loose.
The working yarn is teal, the yarn on the peg is purple.