Erin, think of the hip bone...the top nearest the rear of the cow is the pin bone and the higher sharper bone located in front of that is the hook.

Hooks and pins are bony points of reference on the pelvis. They can be used for measurements, for example the height of a steer calf at the hook at a certain age can give you some idea of its potential frame size and rate of weight gain so that you don't under- or over-feed. They're also used in body condition scoring (see link) and show judging for conformation (ie: line between them is too flat, not flat enough, etc... depending on the breed).

In cattle, the hook is the front-most outside curve of the pelvis, the pin is the rear point, just below and outside the tail.

On a human that would correspond to the top of the hip you can feel just below the waist to the pointy prominence you sit on.

Being "exceptionally long from hooks to pins" doesn't mean too much by itself if 1.) the width and angles of the pelvis aren't in the correct proportion to account for that (regarding calving ease), or 2.) if the pelvis only seems to be exceptionally long because the back or height is exceptionally short (regarding value of meat yield).

If you click on the thumbnail at the bottom of this linked page there's an illustration pointing them out.

Here is a link that might be useful: Body Condition Scoring

Gotcha. Thanks so much for the clarification.