Return a random row of data from an ACF repeater field

random-repeater.php

<?php 

	// Get the repeater field
	$repeater = get_field( 'repeater_field_name' );

	// Get a random rows. Change the second parameter in array_rand() to how many rows you want.
	$random_rows = array_rand( $repeater, 2 );

	// Loop through the random rows if more than one is returned
	if( is_array( $random_rows ) ){

		foreach( $random_rows as $random_row ){

			// Output data here. Replace sub field names.
			echo 'Sub Field 1: ' . $repeater[$random_row]['sub_field_1'] . '<br/>';
			echo 'Sub Field 2: ' . $repeater[$random_row]['sub_field_2'] . '<br/><br/>';

		}

	} else {

		// Output data here. Replace sub field names.
		echo 'Sub Field 1: ' . $repeater[$random_rows]['sub_field_1'] . '<br/>';
		echo 'Sub Field 2: ' . $repeater[$random_rows]['sub_field_2'] . '<br/><br/>';

	}

?>

If you only want one random item from ACF repeater, you can also do:

$repeater = get_field( 'repeater_field_name' );
$rand = rand(0, (count($repeater) - 1));
echo $repeater[$rand]['sub_field_1'];