Function explanation

1

Hello, I just started learning AS a day or 2 ago :glasses:
Now, I don’t really understand how to use functions,
I read the function page on kirupa.com, but I saw other (random) files where the functions included a lot of information between the brackets…
like:
test = function(a, b, c, d, e, …){
}

Could anybody help me understand when/why to use all that data?

I tried google, but than didn’t help :blush:

Thanks,