Upload error notification.

I am receiving error notifications when I try to upload a sketch.
Is there a guide to interpreting what notifications mean?
This is what I am receiving now when I try to flash a arduino nano board:

Arduino: 1.8.10 (Linux), Board: "Arduino Nano, ATmega328P"

/tmp/ccsPuNW8.ltrans0.ltrans.o: In function main': /home/jim/Downloads/arduino-1.8.10/hardware/arduino/avr/cores/arduino/main.cpp:43: undefined reference to setup'
/home/jim/Downloads/arduino-1.8.10/hardware/arduino/avr/cores/arduino/main.cpp:46: undefined reference to `loop'
collect2: error: ld returned 1 exit status
exit status 1
Error compiling for board Arduino Nano.

This report would have more information with
"Show verbose output during compilation"
option enabled in File -> Preferences.

Jim.

It is telling you that the sketch you are trying to compile and upload does not contain a function called setup() and does not contain a function called loop(). The bootloader code demands that both of these functions be present in your sketch.

Thanks for the explanation blh.
I will address that.