Read represents the pages read to get the result of the query. The lower the better.
But when you need aal recordsof a table, all pages must be read.... (unless they are in cache). When not all records must be read there is the 'tuning' part. See that the query does not do a full tables scan if an (new) index can prevent this, that the query is properly build to take advantage of the existing indexes, that as soon as possible only the realy needed records are kept ....
