Custom field in PHP file

Assuming your $hasp_expire_date = get_post_meta( $post_id, ‘hasp_expire_date’, true ); is giving you the correct value you need, you are storing your that in the $hasp_expire_date variable.

So edit that second line to:

$num_comments = get_comments_number( $block_data['id'] );

// Pull in the value you need
$hasp_expire_date = get_post_meta( $post_id, ‘hasp_expire_date’, true );

// You are going to concatenate or add that value to your string.
$entry_comments = $hasp_expire_date.'<i class="fa fa-speech-bubble"></i><span>'.$num_comments.' '._nx( 'Comment', 'Comments', $num_comments, 'comments', 'uncode' ).'</span>';

Hope that helps!!