How to write a program that difines a function named float_funcion() which takes the floating point number as it argument?

Question

I need clue on what does defining mean

Answer 1

Define means to give a name to your function. just like
def any_name_you_would_like_and_related():
And here goes all the code to interpret when the function is called
We call the function by its given name

Answer 2

Defining mean,
Giving definition of a function OR Explaining what a function will do when it is called in terms of programming.