When a sketch plane is activated, a sketch grid is drawn that encompasses all the sketch entities on the plane. The camera updates automatically to look at the sketch plane. If there are no entities on the plane, the grid assumes a default size.
The sketch grid has two icons associated with it:
The grid provides precise snap points defined by its spacing. A red rectangle indicates a snap point.
Snap points are available throughout the sketch plane. They are not restricted to the visible Grid.
You can hide the Grid in two ways:

The snap bar at the bottom-right of the canvas controls the spacing of the sketch grid. If the snap bar is set to 0, the Grid assumes a default spacing value.