Usage by Hits reports the number of requests made in the given time frame. Depending on your hit filter selections, a hit is considered to be any request for data such as a web page, download file, image, or other file.  For example, if you have a web page that had two images, ran one script and played one wave file, there would be five hits for that web page.  The report shows the hour, the number of hits for that hour and the percentage of hits for that hour.