如果你把它分解一下，就会更容易理解。您问题中的代码与此完全相同：

$message = sprintf( __( \'This action will let you pay a deposit of <span class="deposit-price">%s</span> for this product\', \'yith-woocommerce-deposits-and-down-payments\' ), wc_price( $deposit_value ) );
$message = apply_filters( \'yith_wcdp_deposit_only_message\', $message, $deposit_value );

echo wp_kses_post( $message );

但是，您还可以看到过滤器接收$deposit_value 变量作为其第二个参数，这意味着您可以在过滤器中使用它：

<?php
add_filter(
    \'yith_wcdp_deposit_only_message\',
    function( $message, $deposit_value ) {
        $message = \'This is my new message, and the deposit value is \' . wc_price( $deposit_value );
         
        return $message;
    },
    10,
    2 // MUST be 2 to be able to use $deposit_value.
);