There are several types of shots in beach volleyball. One of them is a roll shot.
A roll shot differs from a full speed attack because you're contacting the ball underneath the ball, and finishing rolling on top of it.
A full attack is when you're coming in and hitting on top of the ball. With a roll shot you're actually kind of hitting underneath and curving around it. You can also hit a roll shot on the high end, but you're going to finish with a high snap on top of the ball instead of a full swing contact.
So it's good to go up for a roll shot when you're coming in for a full hit, just keep the ball in front of you so you can see the court and the defender, go up like you're making a full swing hit, and then ease up your arm swing and roll shot on top of the ball, and you can place the ball on any part of the courts, making it very tough to defend.
You're also making the block ineffective when you roll shot, because the block is really there for a hard driven ball, which is that huge hit we talked about earlier. If you're shooting, the block is no longer effective, and you're taking them out of the game. Now it's one on one instead of one on two.
I prefer to poke over the roll shot personally, but a roll shot is great for a highline shot over the block, because you come up high and you finish on top of the ball over on the line. The defender is usually at the angle, so if you highline over, it usually goes down. It's also good for a cut shot, but those usually get dug more often. And those are a couple ways you can use a roll shot in beach volleyball.