It's for local service discovery. Those services may be printers on your network, or another computer sharing music on iTunes (which is why as a Windows user you'd usually get Bonjour when installing iTunes). Or maybe it's your Raspberry Pi.

It feels iffy because it comes bundled with other software without you being asked (IIRC) and it autoruns on startup. And I mean 20 years ago when iPods were a thing and people had to use iTunes on Windows, a couple dozen megabytes of RAM really mattered too. Hell I had 512 MB back when I had an iPod (and therefore iTunes)