str_replace function in theme

function replace_content($text) {
  $replace = array(
    'Check' => '<span style="color:red">Check</span>',
    'Map' => '<span style="color:red">Map</span>',
    'Comments' => '<span style="color:red">Comments</span>',
    'Print' => '<span style="color:red">Print</span>'
  );

  $text = str_replace(array_keys($replace), $replace, $text);
  return $text;
}

add_filter('the_content','replace_content');