The basic rules of beach volleyball are that you're allowed a maximum of three contacts per side. Typically, this would be the pass, the set, and the hit. However, it's also legal to have less than three touches. For instance, you could pass, and your partner could hit it over instead of setting you, that's called "taking an option", or you could pass it directly over the net on your first contact. However, this gives your opponents the best chance of running their own offense, so it's usually best to have three contacts.
You're not allowed to touch the net when you're close to it, either hitting or blocking. You're also not allowed to hit or serve the ball into the net, or outside of the lines. It's legal for your hit or serve to touch the net, as long as it goes over the net. It's not legal for you to double a set, and hand set. That means contacting the ball at separate times with your hands, usually causing it to spin. Also, when you're digging, you're not allowed to double a ball that's not hard driven. If someone hits a ball at you, you're allowed to double it, but if it's a soft shot or a pass, you cannot double it.
In beach volleyball, unlike indoor, the block counts as a touch. When the blocker touches the ball, there are only two touches remaining. However, if the blocker touches the ball, and it lands on the blocker's side, the blocker can then dig the ball, again, bump or dig the ball, and then their partner has to put the ball over the net.
As you're serving, you cannot step into the court until after you've contacted the ball. If you do so, it's called a foot fault. Also, while serving, if you touch the line with your feet, that's also a foot fault. You cannot go outside of the horizontal boundaries of the court when you're serving.
When you play beach volleyball, you can dig the ball with any part of you body, including your foot, your shoulder, your chest, or your head. When you are digging or setting a ball, you can't contact the ball for too long. That's called a lift, or a hold.
And those are the basic rules of beach volleyball.