How can I show only if custom field has content [closed]

Again, I’m not familiar with Advanced Custom Fields but you may be able to store the returned value into a variable then test if that variable is empty, like so:

<?php
    $pista1a = types_render_field("pista-1a", array("argument1"=>"value1","argument2"=>"value2","argument2"=>"value2"));
?>
<ul>

  <?php if( ! empty( $pista1a ) ) : ?>

    <li>
        <?php echo $pista1a; ?>
    </li>

  <?php endif; ?>

</ul>