When you set up a taxonomy field you have the choice to return the Term ID or the Term Object. Either way you need to do a little more work to show the term name.
// returning Term ID
$term_id = get_field('location_assign_client');
// https://codex.wordpress.org/Function_Reference/get_term_by
$term = get_term_by('id', $term_id, $YOUR_TAXONOMY);
echo $term->name;
OR
// returning Term Object
$term = get_field('location_assign_client');
echo $term->name;