Sorry I forgot to add the_row().
<?php
$i = 0;
while(have_rows('squares')):
the_row();
$i++;
$repeater = get_sub_field( 'images' );
$rand = rand(0, (count($repeater) - 1)); //does not select a specific row but rather just a number
?>
<a href="<?php the_sub_field('link'); ?>" class="fs-square" style="background-image:url('<?php echo $repeater[$rand]['four-square']; ?>')">
<div class="main-text"><?php the_sub_field('main_text'); ?></div>
<div class="icon-section">
<div class="icon"><?php the_sub_field('icon'); ?></div>
<div class="icon-text"><?php the_sub_field('icon_text'); ?></div>
</div>
</a>
<?php endwhile; ?>
