translate-string.php

function my_custom_translations( $strings ) {
  $text = array(
    'Related products' => 'Customers Also Viewed',
    'Some other one you like to translate/change' => 'Translate/Change'
  );
  
  $strings = str_ireplace( array_keys( $text ), $text, $strings );
  return $strings;
}

add_filter( 'gettext', 'my_custom_translations', 20 );