MediaWiki:Apihelp-flagconfig-description/en

From translatewiki.net

Get basic information about review flag configuration for this site.

The following parameters are returned for each tag:

name
The key name of this tag.
levels
Number of levels the tag has (above "not tagged").

Flagged revisions have an assigned level for each tag. The highest tier that all the tags meet is the review tier of the entire revision.