Here are the corrections needed for the provided code:
1. There is a typo in the variable name inside the loop; it should be `num` instead of `number`.
2. The variable `nums` is undefined; it should be `numbers` when calling the `calculate_average` function.
Here's the corrected code:
```python
def calculate_average(numbers):
total_sum = 0
for num in numbers:
total_sum = total_sum + num # Changed 'number' to 'num'
average