Glass, such as plate glass or a window pane, can represent:
- Awareness or clarity, especially of situations, events, people, dynamics, etc. out in the world
- Ability to see or be seen
- Transparency, such as a person's thoughts or feelings being easy to read
- Communication, openness, honesty
- Invisible barrier, such as a "glass ceiling" or other situation where you can see something but not get to it, or see someone but not communicate with them
Something being behind glass, such as jewelry in a glass display case, can represent protection, security, or the idea of value, desirability, or preservation.