I think most people would need to understand the precise make and model of the head-unit/tablet in question, to be able to offer up further advise. The screenshot posted seems to indicate things like CarPlay, Android Auto, Bluetooth, WiFi/4G. Presumably, it can connect via Bluetooth to a phone to offer handsfree calling (via the vehicle speakers/mic the head unit is now connected to). However, maybe the indicated Bluetooth is only for connecting other handsfree accessories, to the head unit itself. The CarPlay/AndroidAuto indication presumably means about for connection with an Apple or an Android phone, for normal CarPlay/AndroidAuto features of most traditional head units. Not sure what the 4G indication is about. Perhaps the head unit is capable of having a SIM inserted into it and being connected to a cellular service provider with its own dedicated telephone number (and for receiving/sending calls, text/SMS, etc). Some people would like that. Others may not (instead preferring to only let the phone itself have a cellular connection). Not sure what the WiFi indication means. Perhaps that's only about for connecting between phone and head unit for wireless CarPlay/AndroidAuto (which does make use of WiFi). Or, perhaps the head unit can also be connected (when the vehicle is parked) to a WiFi hotspot.
Did you get an installation, instruction or operating manual, when you got the head-unit/tablet? From where was it purchased?
In my experience, CarPlay and AndroidAuto in vehicles basically aim to fully replace normal vehicle handsfree Bluetooth, and then calls are done through the features of CarPlay/AndroidAuto (not through just plain old Bluetooth handsfree). And, if one wants to not use CarPlay/AndroidAuto for handsfree, then one often needs to disconnect from CarPlay/AndroidAuto, to see if the vehicle/head-unit has a separate Bluetooth handsfree capacity that can be used.