This gist is used in the tutorial https://www.vijayan.in/how-to-create-custom-table-list-in-wordpress-admin-page

get_columns.php

<?php

...
	/**
	 * Get list columns.
	 *
	 * @return array
	 */
	public function get_columns() {
		return array(
			'cb'     => '<input type="checkbox"/>',
			'title'  => __( 'Title', 'admin-table-tut' ),
			'type'   => __( 'Type', 'admin-table-tut' ),
			'author' => __( 'Author', 'admin-table-tut' ),
			'date'   => __( 'Date', 'admin-table-tut' ),
		);
	}
...