This web service parameters describe two main components: query and summary. There can be more one or more queries and one or more summaries. Each query or summmary is written in the format queryN or summaryN respectivley, where the N identifies a sepcific query or summary.
A query has to have metric type, area and period parameters.
The type of value that is returned for each query is defined by the valueType parameter, examples are raw, rank and band.
Summaries again need metric type, area and period. Use summaryType to define the type of summary and summaryFor to define what will be summarised. For example summary types are sum, min and max.
Read this web method's full documentation.