When you're frantic, you're upset, or worried, or very excited, and so you're moving around very quickly.
You might be frantic when you're late for school: you might frantically grab your backpack and your lunch, and frantically search for your shoes. Or, you might be frantic when you've desperately got to get to the bathroom! In that case, you might move around frantically, or in a frantic voice, shout, "I gotta go! I gotta go! I gotta go, now!"