For details, see the wiki (russian and english).

That validator finds similar named POIs and returns table with highlighted tag values that does not match the pattern.

Validator looks for settings in the validator.cfg file. Format of this file:

name_of_file_with_osm_xml_data
tag_that_will_be_searched : needed_value_(case_sensitive)
other_tag : his_value
other_tag : his_value
etc

Script returns html file to stdout and starts web-browser to show result