When we talk about functions, we're talking about things that can take some input and give us some output. Imagine you have a magic box that can turn apples into apple juice - this is a function!
Now, let's say your friend has a lot of apples and wants to make some juice. But they want to add sugar to make it sweeter. You could make a new function that takes in an amount of apples and an amount of sugar, and gives you back the amount of apple juice with sugar added.
But how do we tell the function how much sugar to add? This is where the argument comes in. An argument is a piece of information that we give to the function to help it do its job. It's like telling the function "I want the apple juice to have 2 tablespoons of sugar".
So, the argument of a function is the extra piece of information that we give it when we want it to do something specific. Without arguments, functions don't know what to do - they need specific instructions from us!