Create a Render Texture

A Render Texture is a type of textureAn image used when rendering a GameObject, Sprite, or UI element. Textures are often applied to the surface of a mesh to give it visual detail. More info
See in Glossary that Unity creates and updates at runtime.

You can set a camera to render into a Render Texture. You can then use the Render Texture as the material on a GameObject so the camera view appears on the GameObject.

To create a Render Texture, select Assets > Create > Rendering > Render Texture.