Log collector - size of upload logs to MCAS portal

Hi there folks. I can see in the MCAS > Settings > Governance Log, the "Parse Cloud Discovery log" entries for our incoming proxy input source / log collector data. In the "status" column I can also see...."Successful - 139 MB of data were successfully parsed from xxxxx"

My question is - what is the significance of the xxx MB of data ? Is this the actual size of the uploaded log from the input source, after log collector compression ? Or is this data value just referring to the volume of traffic recorded from the activity in the log and not the actual log file size ?

Thanks.