The Tilemap component is a system which stores and handles Tile Assets for creating 2D levels. It transfers the required information from the Tiles placed on it to other related components such as the Tilemap Renderer and the Tilemap Collider 2D.
Download the 2D Tilemap Editor package via the Package Manager, as it is not included in the Unity Editor installation.
Use this component with the Grid component, or a parent Grid GameObject, to lay out Tiles on the associated Grid. When creating a Tilemap (menu: GameObject > 2D Object > Tilemap), Unity automatically creates a Grid GameObject and sets it as the parent of a child Tilemap GameObject.