Google Knowledge graph refers to a block of information that appears on the right side of the SERPs after entering a search query. It is launched by Google in 2012 and is also known as Knowledge Graph Card.
It provides information systematically using images, content, graphs, etc. It creates interconnected search results to makes information more appealing, accurate, structured and relevant. So, it is an enhancement of the organic Google search results as it understands the facts about, people, places, objects, etc.