Debian is a free operating system (OS) for your computer. An operating system is the set of basic programs and utilities that make your computer run. Debian provides more than a pure OS: it comes with over 59000 packages, precompiled software bundled up in a nice format for easy installation on your machine.
I just updated and noticed some more 'get/hit' lines, repeated the command and there are now only 'hit'. Can anyone explain this process a bit? My apologies if this is a dumb question.
"Hit" means that the local cached file matches the file on the server.
Linux check the file online, and check for change compared to the local file on your computer, if there is a change, then it GET (download) the whole new file, as you can see in the first command!