This is a way of making a fold or a ridge in your knitted work. If the st 7 rows below is at the cast on, it's a way of making a hem.
Put your right hand needle into the purl bump 7 rows below the next st on the left hand needle and lift that st up and slide it onto the left needle. Now purl the 2 sts together. Continue to do this for the rest of the row. It's really a very neat and pretty detail when completed.
At the end of the row, turn and begin the 8 rows of stockinette.