odd rows: k3, k5, p5, k5, k3 = k8, p5, k8
even rows: k3, p5, k5, p5, k3 = k3, p5, k5, p5, k3.
these 2 rows form the stitch pattern so you will repeat these, alternating odd row, then even row. then you change it to the reverse part. and alternate those.
Those 2 sets of k sts in the odd row are just to define the garter st border from the brick pattern.