It is used to encode the message into morse code.
This is my project👇
You will use what you've learnt to create a text-based (command line) program that takes any String input and converts it into Morse Code.
You've created plenty of text-based programs in Days 1 -10, so look back at some of those projects if you don't remember what a text-base program looks like.
Wikipedia Entry for Morse Code
The design, functionality, code style is all up to you. You're wearing the big-girl/big-boy pants now. So you get to decide.