description of mine...
The hooks have a 2" strap that wraps around your wrist (secured by velcro) and a part that comes down across your palm that is relatively hard, and then curves up to form a hook (about 1" wide and covered with fabric). The dumbell or barbell can rest in this hook area while you grasp the dumbell or barbell with your hand and fingers around all of that...the hook and weight. It may sound weird to have that hook in the middle of your palm, but it is not bothersome. It takes a lot of the weight off of your fingers and forearm (but not all...you still have to hold it or it will fall out of your hand). It enables you (or me at least) to do a lot more weight and/or a lot more reps when my hands/forearms feel like they'll give out first on a leg exercise.
The wraps serve the same purpose, but they are basically strips of fabric (some as simple as a length of webbing material, 1-2" wide, fancier ones have a velcro wrist-wrap as part of the arrangement) that you wrap around your hand/wrist/bar such that the end of it tucks under your grip to secure it. Once you get it on, it works just as well (or sometimes better, since the weight can't really "tip" out) than the hooks, but it can be very hard to put on the second one by yourself once the first hand is already wrapped and attached.