It probably means k1, then increase with a kfb in the next stitch. If you usually do a M1 for an increase, you'd k2, M1.
eta: oops, I meant p1, kfb. Then you would continue with K2, kfb, p1. Or if you use M1 for an inc, it'd be p1, k1, M1, k3, M1, p1.