Remember, if you want holograms to work you need a compatible Holograms plugin which are listed on: Requirements
Information Hologram
This hologram will be showed to the player when looking at the turret. You can use the same variables as HERE including %owner%, %level%, %health_bar%, %ammo% and %health_percentage% The health bar variable will display the current health status of the turret. You can change health bar properties in the config.
An additional line will be added to the hologram when it doesn't have ammo or the turret is disabled. This additional line can be modified in the messages.yml file.
This hologram will appear when an entity is shoot by the turret. Remember these properties are used just for this turret, meaning every turret can have different holograms.