Question

The spelling mistakes in content affect which of the usability heuristics

Answer 1

the mistakes are done by the power of the brain

Answer 2

The answer is error prevention.

The spelling mistakes in content affect the error prevention usability heuristics. Error prevents an error from occurring than allowing error messages to occur.

For example, the Search box in Google Search tries to prompt you with the correct spelling when you type a wrong spelling.  Similarly, Outlook reminds you to include an attachment that you have forgotten to but have mentioned about it in the body of your email.