Check the docs
But basically:
<?php
// Check rows exists.
if( have_rows('repeater_field_name',option') ):
// Loop through rows.
while( have_rows('repeater_field_name','option') ) : the_row();
// Load sub field value.
$sub_value = get_sub_field('sub_field');
// Do something...
// End loop.
endwhile;
// No value.
else :
// Do something...
endif;