It is not a ATmega328P.
In the menu, find the Nano Every, then select the COM port.
I think you have to install that board.
In the Arduino IDE, go to the "Board Manager" and install the "Arduino MegaAVR Boards".
Then select in the menu: Tools / Board / Arduino megaAVR boards / Arduino Nano Every
Walk through this page: https://www.arduino.cc/en/Guide/NANOEvery