WordPress at a glance
function is not described

register_block_core_categories() WP 1.0

Registers the core/categories block on server.

No Hooks.

Return

Nothing (null).

Usage

register_block_core_categories();

Code of register block core categories: wp-includes/blocks/categories.php VER 5.1.1

<?php
function register_block_core_categories() {
	register_block_type(
		'core/categories',
		array(
			'render_callback' => 'render_block_core_categories',
		)
	);
}