The switch is on the screen’s Actions tab.
A disabled screen stays in the workspace but stops displaying content and stops using a license.
What survives
Everything except playback. Settings, labels, notes, location, and playlist assignments are all still there, so re-enabling puts the screen back exactly as it was. There is no rebuild and no re-pairing.
When to use it
A screen out of service. A display being repaired, a site closed for refurbishment, a seasonal location. Disabling returns the license to the pool for something else and gives it back when you re-enable.
Freeing a license in a hurry. If a new screen will not pair because the pool is full, disabling something you are not using is faster than changing the plan.
A screen you are not sure about. Disabling is reversible in a way that deleting is not. If you are tidying up and cannot remember what a screen is, disable it and see whether anyone notices.
Enabling after a transfer
A screen moved from another workspace arrives disabled. Open it, enable it, and it starts playing. A transfer that appears to have done nothing has usually just done this.