**Defining a Function** is a crucial concept in programming. In programming languages, a function is a block of code that can be called multiple times from different parts of your program. Here's a step-by-step guide on how to define a function:

* **Function Name**: Choose a unique and descriptive name for your function.
* **Function Signature**: The function signature includes the function name, **parameters** (input values), and **return type** (output value).
* **Function Body**: The function body contains the code that will be executed when the function is called.

**General Syntax:**
```python
def function_name(parameters):
    # function body
    return output_value
```
**Key Components:**

* **`def`**: The keyword used to define a function.
* **`function_name`**: The name of the function.
* **`parameters`**: The input values passed to the function.
* **`return`**: The keyword used to specify the output value of the function.
* **`output_value`**: The value returned by the function.

**Example:**
```python
def greet(name: str) -> str:
    return f"Hello, {name}!"
```
In this example:

* **`greet`** is the function name.
* **`name: str`** is the parameter, which is a string.
* **`-> str`** specifies the return type, which is also a string.
* **`return f"Hello, {name}!"`** is the function body, which returns a greeting message.

**Tips:**

* Use **descriptive names** for your functions and variables.
* Keep your functions **concise** and focused on a single task.
* Use **comments** to explain the purpose of your functions and variables.

I hope this helps you understand how to define a function, Jirwen! Do you have any specific questions or examples you'd like to discuss?