See also: https://eventespresso.com/topic/event-admin-table-list/

event_meta_column.php

<?php
//* Please do NOT include the opening php tag, except of course if you're starting with a blank file

function my_event_table_head( $defaults, $screen ) {
    $defaults['kurs']  = 'Kurs';
    return $defaults;
}
add_filter( 'FHEE_manage_toplevel_page_espresso_events_columns', 'my_event_table_head', 10, 2 );

function my_event_table_content( $event, $screen ) {
    if ( ! $event instanceof EE_Event ) {
        return '';
    }
    echo get_post_meta( $event->ID(), 'meta-box-text', true );
}
add_action( 'AHEE__EE_Admin_List_Table__column_kurs__toplevel_page_espresso_events', 'my_event_table_content', 10, 2 );