With regard to the number of ‘remediated computers’ for a given Fixlet (or baseline) in Web Reports, it is based on the Fixlet first being identified as relevant by the given endpoint, then subsequently no longer relevant. As such, there are multiple factors to consider, including how recently the devices in question have reported in.
That said, with regard to your question, the ‘122’ number above generally comes from how many machines are subscribed to the site containing the content element (in the case above, how many computers are subscribed to the
Windows Server 2012 R2 Updates site). Here’s a sample session relevance that will return this value:
number of subscribed computers of bes custom sites whose (name of it = "Windows Server 2012 R2 Updates")
This session relevance can be evaluated through the REST API via the /api/query resource, or through the SOAP API.