Open Question: In VBA in Excel what is passing parameters and how do you do it?

What is passing parameters?

I read a tip about passing parameters here http://customofficesolutions.net/gpage2.html that got me interested. It said,

"Passing Parameters
Start off right by learning how to pass parameters to other procedures as well as functions. Oftentimes people new to VBA programming will find themselves using a lot of global variables which isn't the best practice. This can often be avoided by passing parameters when you need to carry a value from one piece of code to another. It seems a little strange at first but you quickly get the hang of it after a couple times, so hang in there and learn it. You will be happy you did."

I want to learn this weird way of using variables.

I think I currently use global variables. For example,
I have a module with every variable listed. It looks like:

Sub Hotdogs()
Public var as string, cat as integer, mouse as dog, etc.
Public variable as long, etc.
...

In my modules that use the variables, I may write:
var = "hot dogs" ' or whatever I want the variable "var" to equal.
...

and then I use var to represent hotdogs in the code that follows.

So is this the wrong way? Is passing variables different? Is it better?

Any links for me to learn about this and other good tips would be appreciated too.
Thank you in advance!