Hi Dave,
The usage quantity relates to the number of units purchased or consumed. In other words, it will depend on what you are searching for.
For Azure Database for example, the instance usage & licence units are calculated by the number of hours X number of cores. If you add 'Item description', 'resource ID' & 'Date' dimensions to your report, you should be able to view additional information.
We do have a feature request to add these units details to cloudability but no ETA as of yet.
#Cloudability