The first column (1) show, and control, the cursor position in voxels.

The second column (2) show, and control, the cursor position in mm. If an origin, or relevant sform/qform setting, has been set in the image header, this will be reflected in these values.

The "Volume" field (3) shows and controls the current volume (e.g., timepoint) in a 4D dataset.

"Intensity" (4) shows the value in the voxel at the current cursor position.