i don’t know if i did it right, this is the code i managed to do and it works
<?php
if( have_rows('misure_e_prezzi')):
$rows = get_field('misure_e_prezzi' );
$my_fields = get_field_object('misure_e_prezzi');
$specific_row = $rows[0];
$first_row_price = $specific_row['prezzo' ];
$count = (count($my_fields['value']));
$valuta = '€ ';
?>
<div class='prezzo'>
<?php
if ($count ==1)
echo $valuta .number_format( $first_row_price, 2, ',', ' ');?></div>
<?php
if ($count >1)
echo 'A partire da: '?>
<div class='prezzo'>
<?php
if ($count >1)
echo $valuta .number_format( $first_row_price, 2, ',', ' ');?></div>
<?php
endif;
?>