How to add a text in the checkout page woocomerce?

You have two options. You can use the hook woocommerce_before_thankyou hook to add some html before “Obrigado. Seu pedido foi recebido” or you can replace the that thankyou text with any html you want with the hook woocommerce_thankyou_order_received_text

If you want to use woocommerce_before_thankyou (NOTE: this hook will fire also on failed orders, but you can check inside the hook if the order is failed with the $order_id):

function test_hook_before_thankyou($order_id) {
    echo "teste";
add_action( 'woocommerce_before_thankyou', 'test_hook_before_thankyou' );

If you want to replace that text with the hook woocommerce_thankyou_order_received_text:

function test_hook_replace_thankyou ( $thank_you_msg, $order_obj) { /* here you have the full order object, no only the id */

    $thank_you_msg =  'This is your new thank you message';
    $thank_you_msg .=  '<br><b>You can add html too</b>';
    return $thank_you_msg;
add_filter( 'woocommerce_thankyou_order_received_text', 'test_hook_replace_thankyou' );