No in Morse code
No in Morse code is -. ---: N is dash dot and O is three dashes. At just five symbols, it is one of the shortest words in Morse code.
The one-letter no
In the International Code of Signals, the letter N (-.) on its own means "negative", that is no. Radio operators also use NIL for "I have nothing for you".
Notice that NO and YES start very differently: NO begins with a dash followed by a single dot, YES with a dash dot dash dash. Even at speed, the two are hard to confuse.
Translate anything
Type any word into the Morse code translator to hear it, flash it or download it as audio. Every letter, number and sign is on the Morse code alphabet chart, and the trainer teaches you to read Morse code by ear.