If you want to fill several lines in your Excel file, should you change coordinates.
$i=2;
$S=$objPHPExcel->getActiveSheet();
while($row=extractRow()){
$S->setCellValue('B'.$i, $row['UNIT'])
->setCellValue('C'.$i, $row['NUMBER']); // and all others keys (Alternative: Use fromArray either for a line, or for all of the data within the possibilities)
++$i;
}