There are many different rules for volleyball, but I'm going to specifically tell you the rules of indoor volleyball.
First, the court is 18m by 9m and the free zone around the court is at least 2m. Then the net needs to be at least 1m wide and 9.5m long. However, the height of the net can vary from 1.98m to 2.19m depending on the age group playing. When playing a league team as a child, no jewelry is allowed to be worn unless for religious purposes and both adult and children's teams need to have matching uniforms except for the libero.
Depending on if you're playing rally volleyball or not, each match will be played either to 15 or 25. Indoor volleyball history goes back all the way to 1895 and just keeps improving over time. The rules seem to be constantly changing so make sure you keep up to date on them.
One common question I've seen is indoor volleyball safe during pregnancy. Most doctors would avoid it because of the risk of injury. However, different doctor's recommend different sports to avoid. For example, some doctors think its fine to play volleyball during pregnancy if you've played it all your life. Therefore, I would contact your doctor and I ask what he believes you should do.
Well, just make sure you keep up to date with the rules of indoor volleyball. Whatever type you play, keep up to date on the rules, they're always changing!