Can anyone tell me what exactly this represents:
[87984756 bytes received at 35693 bytes/sec]

in this summary:

HTTrack Website Copier/3.47-23 mirror complete in 41 minutes 5 seconds : 5722
links scanned, 4193 files written (450913467 bytes overall), 1404 files
updated [87984756 bytes received at 35693 bytes/sec]