Can someone explain what's the use of parse request function in WordPress?

What's the meaning of Parses the request to find the correct WordPress query in plain Englush?

Reference: https://developer.wordpress.org/reference/classes/wp/parse_request/

I encountered this function while trying to edit a PayPal gateway plugin as below.

/**
 * Parse request to find correct WordPress query.
 *
 * @since 1.6.4
 * @param WP_Query $wp WordPress Query object.
 */
public function parse_request( $wp ) {  
    if ( array_key_exists( 'acadp_action', $wp-query_vars )  'paypal-ipn' == $wp-query_vars['acadp_action']  array_key_exists( 'acadp_order', $wp-query_vars ) ) {
        $this-process_payment_ipn( $wp-query_vars['acadp_order'] );
        exit();
    }       
}