Add a column to the Users overview in WordPress Admin to display the registration date

admin-column-user-registered-date.php

<?php

/*
 * Create a column. And maybe remove some of the default ones
 * @param array $columns Array of all user table columns {column ID} => {column Name}
 */
add_filter( 'manage_users_columns', 'yanco_modify_user_table' );
function yanco_modify_user_table( $columns ) {
	// unset( $columns['posts'] ); // maybe you would like to remove default columns
	$columns['registration_date'] = 'Registreret'; // add new

	return $columns;
}

/*
 * Fill our new column with the registration dates of the users
 * @param string $row_output text/HTML output of a table cell
 * @param string $column_id_attr column ID
 * @param int $user user ID (in fact - table row ID)
 */
add_filter( 'manage_users_custom_column', 'yanco_modify_user_table_row', 10, 3 );
function yanco_modify_user_table_row( $row_output, $column_id_attr, $user ) {
	$date_format = 'j M, Y H:i';

	switch ( $column_id_attr ) {
		case 'registration_date' :
			return date( $date_format, strtotime( get_the_author_meta( 'registered', $user ) ) );
			break;
		default:
	}

	return $row_output;
}

/*
 * Make our "Registration date" column sortable
 * @param array $columns Array of all user sortable columns {column ID} => {orderby GET-param}
 */
add_filter( 'manage_users_sortable_columns', 'yanco_make_registered_column_sortable' );
function yanco_make_registered_column_sortable( $columns ) {
	return wp_parse_args( array( 'registration_date' => 'registered' ), $columns );
}