I might need help debugging this code. Can you please help me? I'm new to Python, so the error might look weird. My current code is:

```py
def calculate_average(numbers):
    total = sum(numbers)
    length = len(numbers)
    average = total / length
    return average

data = [1, 2, 3, 4, 5]
result = calculate_average(data)
print("The average is: " + result)
```

and the error message is: `TypeError: can only concatenate str (not "float") to str`

What does this error mean, and how can I fix it?
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