You should be able to "Right Click" on the .zip file, and choose extract all files, and then select the location where you would like to put the files, click "OK" and budabing there you go!
It is an "Excel" spreadsheet file, and you need Microsquash Office to open it.
I cut and pasted it to a .txt (and formatted it a few different ways in a .Doc) file and attached it in case you still are having a problem.
Anyway, like I said, it's for Waltham, but Boston might be someting alltogether different.
Also, try this link as well:
EMBA - Fire Pages - Incident Type Codes
Mike