Could any please explain me what I am supposed as stated on this instruction on Elgg docs to copy my elgg installation to another server?

UPDATE elggmetastrings set string = '/var/data/elgg_test/' WHERE id = (SELECT value_id from elggmetadata where name_id = (SELECT * FROM (SELECT id FROM elggmetastrings WHERE string = 'filestore::dir_root') as ms2) LIMIT 1) ;

I don't know MySQL. Could anyone please tell me step by step instruction after getting inside PhpAdmin ...?