WordPress at a glance
function is not described

update_meta() WP 1.2.0

Update post meta data by meta ID.

No Hooks.

Return

true/false.

Usage

update_meta( $meta_id, $meta_key, $meta_value );
$meta_id(int) (required)
$meta_key(string) (required)
Expect Slashed
$meta_value(string) (required)
Expect Slashed

Code of update meta: wp-admin/includes/post.php VER 5.1.1

<?php
function update_meta( $meta_id, $meta_key, $meta_value ) {
	$meta_key   = wp_unslash( $meta_key );
	$meta_value = wp_unslash( $meta_value );

	return update_metadata_by_mid( 'post', $meta_id, $meta_value, $meta_key );
}