Here are the corresponding terms for each of the clues you provided:
- The serve used more by novices: Underhand serve
- More difficult of the two types of serves: Overhand serve
- Skill used to finish a point: Attack or Spike
- Hitting the ball to an empty part of the playing area: Placement
- Version of volleyball played six-on-six: Indoor volleyball
- Version of volleyball played two-on-two: Beach volleyball
- What you would do if you make contact with the ball below shoulder level: Underhand hit
- The boundary where the serve is made: Service line
- What you would do if you make contact with the ball above shoulder level: Overhand hit
- The apparatus used to divide the field of play: Net
Feel free to reach out if you need more information or additional assistance!