Bandwidth (and disk space if you qualify for the upgrade) are unmetered. This is NOT the same as "unlimited." Unmetered simply means that the system does not keep track of it and thus there is no specific quota on your account, it does not mean you can use as much of it as you want -- if your account is found to be using excessive amounts of bandwidth (like hundreds of GB per month, note that this is just an example, not a cutoff point) or disk space (like 20 GB, again just as an example and not a cutoff point), your account will likely be suspended if that usage is found to be in violation of the Terms of Service. If the usage is found to be legitimate (because your site is popular or whatnot) you will likely be asked to upgrade to a paid hosting plan.