The reason why it could sound more complicated is because I will use the Terminal/Command Prompt in this explanation.
Okay, now you should know what a Terminal and a Command Prompt is.
So, why is it not safe to work without IDE? If you work without an IDE, it means you made your program just in a random file. This means you have no program that catches the failure if you made a mistake in your code. This wrong code could have some ugly consequences for your computer. Think of computer get’s stuck into your code or it starts deleting stuff. That’s why it’s safer to use an IDE.