Android Auto allows users with a compatible vehicle to use their vehicle's infotainment screen for Android applications like Waze, music, phone, etc. Google plays my messages, and I can reply to them using Assistant. It effectively replaces the vehicle's "assistant" with Google. Example: I'm not sure where a certain restaurant is. Rather than look it up and punch the location in my vehicle's navigation system, I just tell Google "navigate to Chief's Smokehouse" - Google will do the search, put the address in Waze (or Maps if I choose), and navigate there.
Since you say you have no need of it, you can go to Settings -- Apps -- Overflow Menu (three dots upper right) -- Show system apps and scroll to Android Auto. There you should be able to uninstall it or at least disable it.