Kinsfolk are your family — the people you are related to, not friends you only feel close to. It is a group word: it points to the relatives as a set. You will meet it in older writing, in stories, and in rather formal or folk-sounding speech; most people now just say family or relatives. Though actually, kinsfolk can feel a little wider than the people in your house. It can take in aunts, cousins, and the larger kin-group, the folk who share your blood. You do not usually count it. Careful writing says 'my kinsfolk', not 'three kinsfolks', though you will hear the extra s.