Anything holographic refers in some way to a hologram, which is a three-dimensional, projected image of something or someone.
At the beginning of the first Star Wars movie, there’s a holographic image of Princess Leia projected by R2D2. The image was a hologram: it’s not real, but it’s an accurate 3D image created by light beams. You can use the word holographic for anything pertaining to holograms, including the holographic device that creates the holographic image. The content of the hologram could be called a holographic message. The science of making holograms is called holography.