When you enable automatic grid snapping, the Move, Rotate, and Scale transform tools snap the selected GameObjectThe fundamental object in Unity scenes, which can represent characters, props, scenery, cameras, waypoints, and more. A GameObject’s functionality is defined by the Components attached to it. More info
See in Glossary to the grid along the active gizmoA graphic overlay associated with a GameObject in a Scene, and displayed in the Scene View. Built-in scene tools such as the move tool are Gizmos, and you can create custom Gizmos using textures or scripting. Some Gizmos are only drawn when the GameObject is selected, while other Gizmos are drawn by the Editor regardless of which GameObjects are selected. More info
See in Glossary axis. If you want the GameObject to move in smaller increments, you can modify the values it uses to transform incrementally.
To enable automatic snapping to the grid: