The cursor acts as a central focus point when multiple viewing panes are open, and it selects a voxel whose information will be displayed in the Cursor and Mouse panels on the bottom of the window. It also serves as a centroid for rotation in 3D mode, and when in voxel edit mode (or recon edit mode), the mouse is used for drawing and editing.
Linked Cursor and Mouse
When viewing data in a multiple pane mode, the cursor location is linked in all panes. Moving the red crosshair in one pane, will change the slice number accordingly in all other panes. Alternatively, changing the slice number in one pane will move the crosshair accordingly in all other panes. This helps to effectively navigate through the volume in all orientations at once.
Cursor and Mouse Information
At the bottom of the window, information about the cursor and mouse is displayed. Information displayed under "Cursor" gives you the coordinates of the red crosshair. Information displayed under "Mouse" will give you the coordinates of where the mouse is currently hovering over. If you have a label volume loaded and active as well, it will tell you the number and brain region of the color you are hovering over.