The lamb has two hind legs and five front legs. The two regular legs are normal and regular length, while the three extra legs are varying in length. About two minutes after the birth, the lamb could stand on its own legs and half an hour later could drink milk.
The farmer, Wang Jingfeng, was considering removing the legs, but since the lamb can walk normally with them, he decided against it. It's good that they do not have to be removed, so everyone can go see that Jingfeng's not pulling their leg.
The abnormality is due to abnormal embryo growth, and about one in 7 million sheep are born with additional limbs.