How do I get name and label of fields in user profiles? I want to get the list of fields added to user profiles(listed here admin/config/people/accounts/fields). I need machine name and label of each field. How do I get them?
You can use the field_info_instances() function to get that data:

$fields = field_info_instances('user', 'user');

foreach ($fields as $field) {
  $machine_name = $field['field_name'];
  $label = $field['label'];
}