It refers to a male pattern of hair, i.e. in the moustache and beard areas, or occurring more thickly than usual on the limbs. There may be hairs on the chest or an extension of pubic hair on to the abdomen and thighs. What is considered normal for a woman, and what is considered hirsute, depends on cultural factors and race.
Hirsutism is very common.
Hirsutism is nearly always genetic in origin. Female and male relatives may also have more hair than the average so hirsutism is normal in that family. Unfortunately in our society, to be hirsute is thought unattractive. The only reason that Fashion Models appear to have little hair, is that they spend a lot of time and energy removing it. The problem in these women is that the hairs are more sensitive than normal to small amounts of hormone.