I agree with MikeC. Breed standards will vary, but if you're looking for a general description of what a good beef producing animal looks like, I'll see if I can help you out. A beef animal should possess what the consumer is looking for at the grocery store ie. lots of red meat with minimal fat. That translates into an animal, male or female, that is long bodied, deep from the topline to the belly, and wide when viewed from the front or rear. The rear flank should be filled out, not pinched up and the legs should be set out on the corners of the body. This is indicative of heavy muscling. The rump from hooks to pins should be long and level. The rump should be well developed and the forearm should bulge with muscle. When viewed from the rear, the top of the rump should appear rounded, not square. Squareness in the rump when viewed from behind indicates a heavy fat layer. When the animal walks, it should do so loose and freely, without stiffness. The hind foot should track into the print left by the front when the animal is walking. The hind legs need to have a certain "set" to them with being straight like posts or being curved like a sickle. The pasterns need to have some flex to them to enable this animal to walk long distances to find grass and water. I prefer cattle with adequate bone. By this, I mean fairly big boned animals. The framework needs to be rugged if the animal is going to have a long productive life. To concentrate on the two sexes, a female needs to look feminine. She needs adequate udder development and well developed external genitalia. Her neck needs to be longer, in proportion, than a bull's. A cow or heifer should have a more refined head than a bull. These are indicators that she may be reproductuvely sound. Masculine appearing females may not be reliable breeders. On the other hand, a bull should appear rugged and burly. He should have a well developed crest over the neck, a more massive, broad head, and proper testicular development for his age. He should exhibit aggressiveness when it comes to checking cows for heat (libido). A thick neck, bulging forearm, and well developed hindquarters are traits to look for.
I don't know if this is exactly what you were asking for, and it is not a complete description of the ideal beef animal, but maybe I've helped some. DOC and some others may be able to give you a more detailed answer to your question.