Let's look closely at the line of code that we wrote:
renderer.enabled = false;
The semicolon at the end of the line is like the period at the end of a sentence. Nearly all single-line statements must end in a semicolon or the code might break. When code breaks, Unity uses a special popped-up window called the console to tell us about it. When you have code that throws an error, we say there is a bug in your code.
So why doesn't the function declaration have a semicolon? Why don't the curly braces each have one? It's because they're a different beast. They're not a single line of code they're more like a house where code lives. If you start seeing the declaration and statement block as one complete thing instead ...