A function has an input and an ouput. Each input can only have one output.
Examples of functions:
x = y
y = x2
y = cos(x)
where y is the output and x is the input.
photosythnisis
why is the function of chlorophyll in leaves?
The function of the whale are is very intenseful. It makes it fly.
it makes your mom fat
it makes insulin
BOLD?
makes it fluffy
makes energy for the cell to use
Your question makes no sense.
It makes you big and strong!
It makes the light diverge.
Empty parenthesis is a self invoked function that is executed immediately after its created. IT makes the function an expression and any subsequent function, the call.