The function takes a string input and returns the reverse of that string.

[CODE]:
```python
def reverse_string(s):
    return s[::-1]

# Example usage
input_string = "Hello"
output_string = reverse_string(input_string)
print(output_string)
```

This code defines a function called `reverse_string` that takes a string `s` as input and returns the reverse of that string. Additionally, an example usage is provided where the function is called with the input string "Hello" and the returned reversed string is printed.