您的问题中提供的代码不完整,应该是这样的：
// Enabling and Displaying Fields in backend
add_action( 'woocommerce_product_options_general_product_data', 'woo_add_custom_general_fields' );
function woo_add_custom_general_fields() {
global $woocommerce, $post;
echo '
';
woocommerce_wp_text_input( array( // Text Field type
'id' => '_conditions',
'label' => __( 'Conditions', 'woocommerce' ),
'placeholder' => 'i.e: brand-new; refurbished; defected...',
'desc_tip' => 'true',
'description' => __( 'Enter the conditions of the products here.', 'woocommerce' )
) );
woocommerce_wp_text_input( array( // Text Field type
'id' => '_brands', // ===> NOT '_bands'
'label' => __( 'Brands', 'woocommerce' ),
'placeholder' => 'i.e: Lacoste; Hugo Boss...etc',
'desc_tip' => 'true',
'description' => __( 'Enter names of the Brands of the products if any.', 'woocommerce' )
));
echo '
'; // Closing tag HERE
